GIFT   OF 
BOHEMIAN  CLUB 


From  the  collection  of  the 


7 

m 


PreTinger 

i     a 

Uibrary 


San  Francisco,  California 
2006 


i 


ASTRONOMY   FOR  AMATEURS 


Paul  Renaud. 


CONTEMPLATION 


ASTRONOMY    FOR 
AMATEURS 


BY 


CAMILLE    FLAMMARION 

// 

AUTHOR  OF  POPULAR  ASTRONOMY 


AUTHORIZED  TRANSLATION  BV 

FRANCES    A.    WELBY 


ILLUSTRATED 


NEW   YORK    AND    LONDON 

D.  APPLETON   AND   COMPANY 
1915 


.  tv 


COFVRIGHT,   1904,  BV 

D.  APPLETON  AND  COMPANY7 


QM1 
T  '-/• 


Printed  in  the  United  States  of  America 


TO 

MADAME  C.   R.   CAVARE 

ORIGINAL  MEMBER  OF  THE  ASTRONOMICAL  SOCIETY  OF  FRANC* 

CHATEAU   DE   MAUPERTHUIS 


MADAME  :  I  have  dedicated  none  of  my  works,  save  Stella 
— offered  to  the  liberal-minded,  the  free  and  generous  friend 
of  progress,  and  patron  of  the  sciences,  James  Gordon  Bennett, 
editor  of  the  New  York  Herald.  In  this  volume,  Madame,  I 
make  another  exception,  and  ask  your  permission  to  offer  it  to 
the  first  woman  who  consented  to  be  enrolled  in  the  list  of  mem- 
bers of  the  Astronomical  Society  of  France,  as  foundress  of  this 
splendid  work,  from  the  very  beginning  of  our  vast  association 
(1887);  and  who  also  desired  to  take  part  in  the  permanent 
organization  of  the  Observatory  at  Juvisy,  a  task  of  private 
enterprise,  emancipated  from  administrative  routine.  An 
Astronomy  for  Women  *  can  not  be  better  placed  than  upon 
the  table  of  a  lady  whose  erudition  is  equal  to  her  virtues, 
and  who  has  consecrated  her  long  career  to  the  pursuit  and 
service  of  the  Beautiful,  the  Good,  and  the  True. 

CAMILLE  FLAMMARION. 

OBSERVATORY  OF  JUVISY,   November,  sgoj. 

*  The  French  edition  of  this  book  is  entitled  Astronomy  for  Women.— 
TRANSLATOR. 


701029 


CONTENTS 


CHAPTER  PAGE 

INTRODUCTION  i 

I.   THE  CONTEMPLATION  OF  THE  HEAVENS.        .  10 

II.   THE  CONSTELLATIONS 28 

III.  THE  STARS,  SUNS  OF  THE  INFINITE.    A  JOUR- 

NEY THROUGH  SPACE 56 

IV.  OUR  STAR  THE  SUN 88 

V.   THE   PLANETS.      A.    MERCURY,  VENUS,   THE 

EARTH,  MARS 113 

VI.   THE  PLANETS.    B.  JUPITER,  SATURN,  URANUS, 

NEPTUNE 146 

VII.   THE  COMETS 172 

VIII.  THE  EARTH 205 

IX.    THE  MOON .        .232 

X.   THE  ECLIPSES    . 259 

XI.  ON   METHODS.      How   CELESTIAL   DISTANCES 
ARE  DETERMINED,  AND  How  THE  SUN  is 

WEIGHED 287 

XII.  LIFE,  UNIVERSAL  AND  ETERNAL      .        ,        .317 

INDEX 34I 


VII 


LIST  OF  ILLUSTRATIONS 


Contemplation Frontispiece 

From  a  painting  by  Paul  Renaud 

FIG.  PAGE 

1.  The  great  Book  of  the  Heavens  is  open  to  all  eyes  .        .     15 

2.  The  earth  in  space.     June  solstice,  mid-day  .        .        .20 

3.  The  Great  Bear  (or  Dipper)  and  the  Pole  Star    .        .    34 

4.  To  find  the  Pole  Star .35 

5.  To  find  Cassiopeia 37 

6.  To  find  Pegasus  and  Andromeda  .         .        .        .        -37 

7.  Perseus,  the  Pleiades,  Capella 38 

8.  To  find  Arcturus,  the  Herdsman,  and  the  Northern 

Crown 40 

9.  The  Swan,  Vega,  the  Eagle 41 

10.  The  Constellations  of  the  Zodiac:  summer  and  autumn; 

Capricorn,  Archer,  Scorpion,  Balance,  Virgin,  Lion.     46 

11.  The  Constellations  of  the  Zodiac:  winter  and  spring; 

Crab,  Twins,  Bull,  Ram,  Fishes,  Water-Carrier       .    47 

12.  Orion  and  his  celestial  companions     .        .        .        .48 

13.  Winter  Constellations 51 

14.  Spring  Constellations 52 

15.  Summer  Constellations 53 

16.  Autumn  Constellations 54 

17.  The  double  star  Mizar      »        .        .        .        .        .69 

Lx 


ASTRONOMY  FOR  AMATEURS 

riG.  PAGE 

18.  Triple  star  I  in  Cancer 72 

19.  Quadruple  star  e  of  the  Lyre        .....     73 

20.  Sextuple  star  6  in  the  Nebula  of  Orion         ...     74 

21.  The  Star-Cluster  in  Hercules 79 

22.  The  Star-Cluster  in  the  Centaur 80 

23.  The  Nebula  in  Andromeda 81 

24.  Nebula  in  the  Greyhounds 82 

25.  The  Pleiades 83 

26.  Occultation  of  the  Pleiades  by  the  Moon      .        .        .85 

27.  Stellar  dial  of  the  double  star  v  of  the  Virgin  .        .        .86 

28.  Comparative  sizes  of  the  Sun  and  Earth      .        .        .93 

29.  Direct  photograph  of  the  Sun 96 

30.  Telescopic  aspect  of  a  Sun-Spot 97 

31.  Rose-colored  solar  flames  228,000  kilometers  (141,500 

miles)  in  heigth,  i.e.,  18  times  the  diameter  of  the 
Earth 103 

32.  Orbits  of  the  four  Planets  nearest  to  the  Sun      .        .115 

33.  Orbits  of  the  four  Planets  farthest  from  the  Sun  .        .116 

34.  Mercury  near  quadrature     .  ...  117 

35.  The  Earth  viewed  from  Mercury         .        ,        .        .119 

36.  The  Evening  Star 123 

37.  Successive  phases  of  Venus 124 

38.  Venus  at  greatest  brilliancy 126 

39.  The  Earth  viewed  from  Venus 130 

40.  Diminution  of  the  polar  snows  of  Mars  during  the 

summer 136 

41.  Telescopic  aspect  of  the  planet  Mars  (Feb.,  1901)        .  137 

42.  Telescopic  aspect  of  the  planet  Mars  (Feb.,  1901)       .  13* 

z 


LIST  OF  ILLUSTRATIONS 


PIG. 

43.  Chart  of  Mars      .......        .  140 

44.  The  Earth  viewed  from  Mars      .....  144 

45.  Telescopic  aspect  of  Jupiter         .....  150 

46.  Jupiter  and  his  four  principal  satellites        .        .        .  155 

47.  Saturn  .........  159 

48.  Varying  perspective  of  Saturn's  Rings,  as  seen  from 

the  Earth  .........  161 

49.  The  Great  Comet  of  1858    ......  174 

50.  What  our  Ancestors  saw  in  a  Comet    .         .        .        .177 

After  Ambroise  Pare"  (1858) 

51.  Prodigies  seen  in  the  Heavens  by  our  Forefathers        .  178 

52.  The  orbit  of  a  Periodic  Comet     .....  182 

53.  The  tails  of  Comets  are  opposed  to  the  Sun  .  185 

54.  A  Meteor     .........  191 

55.  Shooting  Stars  of  November  12,  1799  ....  196 

From  a  contemporary  drawing 

56.  Fire-Bali  seen  from  the  Observatory  at  Juvisy,  August 

10,  1899   ...  .....  199 

57.  Explosion  of  a  Fire-Bali  above  Madrid,  February  10, 

1896         ........        .  200 

58.  Raphael's  Fire-Bali  (The  Madonna  of  Foligno)    .        .  202 

59.  A  Uranolith          ........  203 

60.  Motion  of  the  Earth  round  the  Sun      ....  222 

61.  Inclination  of  the  Earth       ......  224 

62.  The  divisions  of  the  globe.    Longitudes  and  latitudes  226 

63.  To  find  the  long  and  short  months       ....  230 

64.  The  Full  Moon  slowly  rises          .....  234 

65.  The  Moon  viewed  with  the  unaided  eye  .        .  236 

66.  The  Man's  head  in  the  Moon      .....  237 

xi 


ASTRONOMY   FOR   AMATEURS 

FIG.  PAGE 

67.  Woman's  head  in  the  Moon 238 

68.  The  kiss  in  the  Moon '  .  239 

69.  Photograph  of  the  Moon ,  240 

70.  The  Moon's  Phases 241 

71.  Map  of  the  Moon        .......  247 

72.  The  Lunar  Apennines          .        .        .        .        .        .251 

73.  Flammarion's  Lunar  Ring 253 

74.  Lunar  landscape  with  the  Earth  in  the  sky    .        .        .  254 

75.  Battle  between  the  Medes  and  Lydians  arrested  by  an 

Eclipse  of  the  Sun 266 

76.  Eclipse  of  the  Moon  at  Laos  (February  27,  1877)         .  269 

77.  The  path  of  the  Eclipse  of  May  28,  1900     .         .        .273 

78.  Total  eclipse  of  the  Sun,  May  28,  1900,  as  observed 

from  Elche  (Spain) 281 

79.  The  Eclipse  of  May  28,  1900,  as  photographed  by 

King  Alfonso  XIII,  at  Madrid 285 

80.  Measurement  of  Angles 289 

81.  Division  of  the  Circumference  into  360  degrees    .         .  291 

82.  Measurement  of  the  distance  of  the  Moon    .         .        .  292 

83.  Measurement  of  the  distance  of  the  Sun       .        .        .  297 

84.  Small  apparent  ellipses  described   by  the  stars  as  a 

result  of  the  annual  displacement  of  the  Earth       .  306 


Xll 


INTRODUCTION 


THE  Science  of  Astronomy  is  sublime  and  beautiful. 
Noble,  elevating,  consoling,  divine,  it  gives  us  wings, 
and  bears  us  through  Infinitude.  In  these  ethereal 
regions  all  is  pure,  luminous,  and  splendid.  Dreams 
of  the  Ideal,  even  of  the  Inaccessible,  weave  their  subtle 
spells  upon  us.  The  imagination  soars  aloft,  and  aspires 
to  the  sources  of  Eternal  Beauty. 

What  greater  delight  can  be  conceived,  on  a  fine 
spring  evening,  at  the  hour  when  the  crescent  moon  is 
shining  in  the  West  amid  the  last  glimmer  of  twilight, 
than  the  contemplation  of  that  grand  and  silent  spec- 
tacle of  the  stars  stepping  forth  in  sequence  in  the  vast 
Heavens  ?  All  sounds  of  life  die  out  upon  the  earth, 
the  last  notes  of  the  sleepy  birds  have  sunk  away,  the 
Angelus  of  the  church  hard  by  has  rung  the  close  of 
day.  But  if  life  is  arrested  around  us,  we  may  seek  it 
in  the  Heavens.  These  incandescing  orbs  are  so  many 
points  of  interrogation  suspended  above  our  heads  in 
the  inaccessible  depths  of  space.  .  .  .  Gradually  they  mul- 
tiply. There  is  Venus,  the  white  star  of  the  shepherd. 
There  Mars,  the  little  celestial  world  so  near  our  own. 

I 


l"  t  ;  ASTRONOMY  FOR  AMATEURS 

'There  the  'gianV  Jupiter.  The  seven  stars  of  the  Great 
Bear  seem  to  point  out  the  pole,  while  they  slowly 
revolve  around  it.  ...  What  is  this  nebulous  light  that 
blanches  the  darkness  of  the  heavens,  and  traverses 
the  constellations  like  a  celestial  path  ?  It  is  the  Galaxy, 
the  Milky  Way,  composed  of  millions  on  millions  of 
suns!  .  .  .  The  darkness  is  profound,  the  abyss  immense. 
.  .  .  See!  Yonder  a  shooting  star  glides  silently  across 
the  sky,  and  disappears!  .  .  . 

Who  can  remain  insensible  to  this  magic  spectacle 
of  the  starry  Heavens  ?  Where  is  the  mind  that  is  not 
attracted  to  these  enigmas  ?  The  intelligence  of  the 
amateur,  the  feminine,  no  less  than  the  more  material 
and  prosaic  masculine  mind,  is  well  adapted  to  the  con- 
sideration of  astronomical  problems.  Women,  indeed, 
are  naturally  predisposed  to  these  contemplative  studies. 
And  the  part  they  are  called  to  play  in  the  education 
of  our  children  is  so  vast,  and  so  important,  that  the 
elements  of  Astronomy  might  well  be  taught  by  the 
young  mother  herself  to  the  budding  minds  that  are 
curious  about  every  issue — whose  first  impressions 
are  so  keen  and  so  enduring. 

Throughout  the  ages  women  have  occupied  them- 
selves successfully  with  Astronomy,  not  merely  in  its 
contemplative  and  descriptive,  but  also  in  its  mathe- 
matical aspects.  Of  such,  the  most  illustrious  was  the 

2 


INTRODUCTION 

beautiful  and  learned  Hypatia  of  Alexandria,  born 
in  the  year  375  of  our  era,  public  lecturer  on  geometry, 
algebra,  and  astronomy,  and  author  of  three  works 
of  great  importance.  Then,  in  that  age  of  ignorance 
and  fanaticism,  she  fell  a  victim  to  human  stupidity 
and  malice,  was  dragged  from  her  chariot  while  cross- 
ing the  Cathedral  Square,  in  March,  415,  stripped  of 
her  garments,  stoned  to  death,  and  burned  as  a  dis- 
honored witch! 

Among  the  women  inspired  with  a  passion  for  the 
Heavens  may  be  cited  St.  Catherine  of  Alexandria,  ad- 
mired for  her  learning,  her  beauty  and  her  virtue.  She 
was  martyred  in  the  reign  of  Maximinus  Daza,  about 
the  year  312,  and  has  given  her  name  to  one  of  the  lunar 
rings. 

Another  celebrated  female  mathematician  was 
Madame  Hortense  Lepaute,  born  in  1723,  who  col- 
laborated with  Clairaut  in  the  immense  calculations 
by  which  he  predicted  the  return  of  Halley's  Comet. 
"Madame  Lepaute/'  wrote  Lalande,  "gave  us  such 
immense  assistance  that,  without  her,  we  should  never 
have  ventured  to  undertake  this  enormous  labor,  in  which 
it  was  necessary  to  calculate  for  every  degree,  and  for 
a  hundred  and  fifty  years,  the  distances  and  forces  of  the 
planets  acting  by  their  attraction  on  the  comet.  Dur- 
ing more  than  six  months,  we  calculated  from  morning 

2  3 


ASTRONOMY  FOR    AMATEURS 

to  night,  sometimes  even  at  table,  and  as  the  result  of 
this  forced  labor  I  contracted  an  illness  that  has  changed 
my  constitution  for  life;  but  it  was  important  to  pub- 
lish the  result  before  the  arrival  of  the  comet." 

This  extract  will  suffice  for  the  appreciation  of  the 
scientific  ardor  of  Madame  Lepaute.  We  are  indebted 
to  her  for  some  considerable  works.  Her  husband 
was  clock-maker  to  the  King.  "To  her  intellectual 
talents,"  says  one  of  her  biographers,  "were  joined  all 
the  qualities  of  the  heart.  She  was  charming  to  a  de- 
gree, with  an  elegant  figure,  a  dainty  foot,  and  such 
a  beautiful  hand  that  Voiriot,  the  King's  painter,  who 
had  made  a  portrait  of  her,  asked  permission  to  copy  it, 
in  order  to  preserve  a  model  of  the  best  in  Nature."  And 
then  we  are  told  that  learned  women  can  not  be  good- 
looking!  .  .  . 

The  Marquise  du  Chatelet  was  no  less  renowned. 
She  was  predestined  to  her  career,  if  the  following  anec- 
dote be  credible.  Gabrielle-Emilie  de  Breteuil,  born 
in  1706  (who,  in  1725,  was  to  marry  the  Marquis  du 
Chatelet,  becoming,  in  1733,  the  most  celebrated 
friend  of  Voltaire),  was  four  or  five  years  old  when  she 
was  given  an  old  compass,  dressed  up  as  a  doll,  for  a 
plaything.  After  examining  this  object  for  some  time, 
the  child  began  angrily  and  impatiently  to  strip  off  the 
silly  draperies  the  toy  was  wrapped  in,  and  after  turning 

4 


INTRODUCTION 

it  over  several  times  in  her  little  hands,  she  divined  its 
uses,  and  traced  a  circle  with  it  on  a  sheet  of  paper.  To 
her,  among  other  things,  we  owe  a  precious,  and  indeed 
the  only  French,  translation  of  Newton's  great  work  on 
universal  gravitation,  the  famous  Principia,  and  she  was, 
with  Voltaire,  an  eloquent  propagator  of  the  theory  of 
attraction,  rejected  at  that  time  by  the  Academic  des 
Sciences. 

Numbers  of  other  women  astronomers  might  be 
cited,  all  showing  how  accessible  this  highly  abstract 
science  is  to  the  feminine  intellect.  President  des 
Drosses,  in  his  charming  Voyage  en  Italic,  tells  of  the 
visit  he  paid  in  Milan  to  the  young  Italian,  Marie 
Agnesi,  who  delivered  harangues  in  Latin,  and  was 
acquainted  with  seven  languages,  and  for  whom  mathe- 
matics held  no  secrets.  She  was  devoted  to  algebra  and 
geometry,  which,  she  said,  "are  the  only  provinces  of 
thought  wherein  peace  reigns."  Madame  de  Charriere 
expressed  herself  in  an  aphorism  of  the  same  order:  "An 
hour  or  two  of  mathematics  sets  my  mind  at  liberty, 
and  puts  me  in  good  spirits:  I  feel  that  I  can  eat  and 
sleep  better  when  I  have  seen  obvious  and  indisputable 
truths.  This  consoles  me  for  the  obscurities  of  religion 
and  metaphysics,  or  rather  makes  me  forget  them;  I 
am  thankful  there  is  something  positive  in  this  world." 
And  did  not  Madame  de  Blocqueville,  last  surviving 

s 


ASTRONOMY  FOR  AMATEURS 

daughter  of  Marshal  Davout,  who  died  in  1892,  ex- 
claim in  her  turn:  "Astronomy,  science  of  sciences! 
by  which  I  am  attracted,  and  terrified,  and  which  I  adore  I 
By  it  my  soul  is  detached  from  the  things  of  this  world, 
for  it  draws  me  to  those  unknown  spheres  that  eT'OK  ^d 
from  Newton  the  triumphant  cry:  'C&li  enarta.*,  P'O- 
n'am  Dei!'  " 

Nor  must  we  omit  Miss  Caroline  Herschel,  sister  of 
the  greatest  observer  of  the  Heavens,  the  grandest  dis- 
coverer of  the  stars,  that  has  ever  lived.  Astronomy 
gave  her  a  long  career;  she  discovered  no  less  than 
seven  comets  herself,  and  her  patient  labors  preserved 
her  to  the  age  of  ninety-eight. — And  Mrs.  Somerville, 
to  whom  we  owe  the  English  translation  of  Laplace's 
Mecanique  celeste,  of  whom  Humboldt  said,  "In 
pure  mathematics,  Mrs.  Somerville  is  absolutely  su- 
perior.*' Like  Caroline  Herschel,  she  was  almost  a 
centenarian,  appearing  always  much  younger  than  her 
years:  she  died  at  Naples,  in  1872,  at  the  age  of  ninety- 
two. — So,  too,  the  Russian  Sophie  Kovalevsky,  de- 
scendant of  Mathias  Corvinus,  King  of  Hungary,  who, 
an  accomplished  mathematician  at  sixteen,  married 
at  eighteen,  in  order  to  follow  the  curriculum  at  the 
University  (then  forbidden  to  unmarried  women);  ar- 
ranging with  her  young  husband  to  live  as  brother  and 
sister  until  their  studies  should  be  completed.  In  1888 

6 


INTRODUCTION 

the  Prix  Bordin  of  the  Institut  was  conferred  on  her. 
— And  Maria  Mitchell  of  the  United  States,  for 
whom  Le  Verrier  gave  a  fete  at  the  Observatory  of  Paris, 
and  who  was  exceptionally  authorized  by  Pope  Pius  IX 
to  visit  the  Observatory  of  the  Roman  College,  at  that 
time  an  ecclesiastical  establishment,  closed  to  women. 
— And  Madame  Scarpellini,  the  Roman  astronomer, 
renowned  for  her  works  on  shooting  stars,  whom 
the  author  had  the  honor  of  visiting,  in  company  with 
Father  Secchi,  Director  of  the  Observatory  mentioned 
above. 

At  the  present  time,  Astronomy  is  proud  to  reckon 
among  its  most  famous  workers  Miss  Agnes  Clerke, 
the  learned  Irishwoman,  to  whom  we  owe,  inter  alia, 
an  excellent  History  of  Astronomy  in  the  Nineteenth 
Century; — Mrs.  Isaac  Roberts,  who,  under  the  familiar 
name  of  Miss  Klumpke,  sat  on  the  Council  of  the  Astro- 
nomical Society  of  France,  and  is  D.  Sc.  of  the  Faculty  of 
Paris  and  head  of  the  Bureau  for  measuring  star  pho- 
tographs at  the  Observatory  of  Paris  (an  American  who 
became  English  by  her  marriage  with  the  astronomer 
Roberts,  but  is  not  forgotten  in  France); — Mrs.  Flem- 
ing, one  of  the  astronomers  of  the  Observatory  at  Har- 
vard College,  U.  S.  A.,  to  whom  we  owe  the  discovery 
of  a  great  number  of  variable  stars  by  the  examination 
of  photographic  records,  and  by  spectral  photography; — 

7, 


ASTRONOMY  FOR  AMATEURS 

Lady  Huggins,  who  in  England  is  the  learned  collabora- 
tor of  her  illustrious  husband; — and  many  others. 

The  following  chapters,  which  aim  at  summing  up 
the  essentials  of  Astronomy  in  twelve  lessons  for  ama- 
teurs, will  not  make  astronomers  or  mathematicians  of 
my  readers — much  less  prigs  or  pedants.  They  are 
designed  to  show  the  constitution  of  the  Universe,  in  its 
grandeur  and  its  beauty,  so  that,  inhabiting  this  world, 
we  may  know  where  we  are  living,  may  realize  our  po- 
sition in  the  Cosmos,  appreciate  Creation  as  it  is,  and 
enjoy  it  to  better  advantage.  This  sun  by  which  we 
live,  this  succession  of  months  and  years,  of  days  and 
nights,  the  apparent  motions  of  the  heavens,  these  starry 
skies,  the  divine  rays  of  the  moon,  the  whole  totality  of 
things,  constitutes  in  some  sort  the  tissue  of  our  existence, 
and  it  is  indeed  extraordinary  that  the  inhabitants  of  our 
planet  should  almost  all  have  lived  till  now  without 
knowing  where  they  are,  without  suspecting  the  mar- 
vels of  the  Universe. 

For  the  rest,  my  little  book  is  dedicated  to  a  woman, 
muse  and  goddess — the  charming  enchantress  Urania, 
fit  companion  of  Venus,  ranking  even  above  her  in  the 
choir  of  celestial  beauties,  as  purer  and  more  noble, 
dominating  with  her  clear  glance  the  immensities  of 

8 


INTRODUCTION 

the  universe.  Urania,  be  it  noted,  is  feminine,  and 
never  would  the  poetry  of  the  ancients  have  imagined 
a  masculine  symbol  to  personify  the  pageant  of  the 
heavens.  Not  Uranus,  nor  Saturn,  nor  Jupiter  can 
compare  with  the  ideal  beauty  of  Urania. 

Moreover,  I  have  before  me  two  delightful  books, 
in  breviary  binding,  dated  the  one  from  the  year  1686, 
the  other  from  a  century  later,  1786.  The.  first  was 
written  by  Fontenelle  for  a  Marquise,  and  is  entitled 
Entretiens  sur  la  Pluralite  des  Mondes.  In  this,  banter 
is  pleasantly  married  with  science,  the  author  declaring 
that  he  only  demands  from  his  fair  readers  the  amount 
of  application  they  would  concede  to  a  novel.  The 
second  is  written  by  Lalande,  and  is  called  Astronomic 
des  Dames.  In  addressing  myself  to  both  sexes,  I  am 
in  honorable  company  with  these  two  sponsors  and 
esteem  myself  the  better  for  it. 


CHAPTER   I 
THE   CONTEMPLATION    OF   THE   HEAVENS 

THE  crimson  disk  of  the  Sun  has  plunged  beneath 
the  Ocean.  The  sea  has  decked  itself  with  the  burning 
colors  of  the  orb,  reflected  from  the  Heavens  in  a  mirror 
of  turquoise  and  emerald.  The  rolling  waves  are  gold 
and  silver,  and  break  noisily  on  a  shore  already  darkened 
by  the  disappearance  of  the  celestial  luminary. 

We  gaze  regretfully  after  the  star  of  day,  that  poured 
its  cheerful  rays  anon  so  generously  over  many  who 
were  intoxicated  with  gaiety  and  happiness.  We  dream, 
contemplating  the  magnificent  spectacle,  and  in  dream- 
ing forget  the  moments  that  are  rapidly  flying  by.  Yet 
the  darkness  gradually  increases,  and  twilight  gives  way 
to  night. 

The  most  indifferent  spectator  of  the  setting  Sun 
as  it  descends  beneath  the  waves  at  the  far  horizon, 
could  hardly  be  unmoved  by  the  pageant  of  Nature 
at  such  an  impressive  moment. 

The  light  of  the  Crescent  Moon,  like  some  fairy  boat 
suspended  in  the  sky,  is  bright  enough  to  cast  chan- 
ging and  dancing  sparkles  of  silver  upon  the  ocean.  The 

10 


THE   CONTEMPLATION  OF   THE   HEAVENS 

Evening  Star  declines  slowly  in  its  turn  toward  the  west- 
ern horizon.  Our  gaze  is  held  by  a  shining  world  that 
dominates  the  whole  of  the  occidental  heavens.  This 
is  the  "  Shepherd's  Star,"  Venus  of  rays  translucent. 

Little  by  little,  one  by  one,  the  more  brilliant  stars 
shine  out.  Here  are  the  white  Vega  of  the  Lyre,  the 
burning  Arcturus,  the  seven  stars  of  the  Great  Bear, 
a  whole  sidereal  population  catching  fire,  like  innu- 
merable eyes  that  open  on  the  Infinite.  It  is  a  new  life 
that  is  revealed  to  our  imagination,  inviting  us  to  soar 
into  these  mysterious  regions. 

O  Night,  diapered  with  fires  innumerable!  hast 
thou  not  written  in  flaming  letters  on  these  Constella- 
tions the  syllables  of  the  great  enigma  of  Eternity  ? 
The  contemplation  of  thee  is  a  wonder  and  a  charm. 
How  rapidly  canst  thou  efface  the  regrets  we  suffered 
on  the  departure  of  our  beloved  Sun  !  What  wealth, 
what  beauty  hast  thou  not  reserved  for  our  enraptured 
souls  !  Where  is  the  man  that  can  remain  blind  to 
such  a  pageant  and  deaf  to  its  language! 

To  whatever  quarter  of  the  Heavens  we  look,  the 
splendors  of  the  night  are  revealed  to  our  astonished 
gaze.  These  celestial  eyes  seem  in  their  turn  to  gaze 
at,  and  to  question  us.  Thus  indeed  have  they  ques- 
tioned every  thinking  soul,  so  long  as  Humanity  has 
existed  on  our  Earth.  Homer  saw  and  sung  these 

II 


ASTRONOMY  FOR  AMATEURS 

self-same  stars.  They  shone  upon  the  slow  succession 
of  civilizations  that  have  disappeared,  from  Egypt  of 
the  period  of  the  Pyramids,  Greece  at  the  time  of  the 
Trojan  War,  Rome  and  Carthage,  Constantine  and 
Charlemagne,  down  to  the  Twentieth  Century.  The 
generations  are  buried  with  the  dust  of  their  ancient 
temples.  The  Stars  are  still  there,  symbols  of  Eternity. 

The  silence  of  the  vast  and  starry  Heavens  may 
terrify  us;  its  immensity  may  seem  to  overwhelm  us. 
But  our  inquiring  thought  flies  curiously  on  the  wings 
of  dream,  toward  the  remotest  regions  of  the  visible. 
It  rests  on  one  star  and  another,  like  the  butterfly  on 
the  flower.  It  seeks  what  will  best  respond  to  its  as- 
pirations: and  thus  a  kind  of  communication  is  estab- 
lished, and,  as  it  were,  protected  by  all  Nature  in  these 
silent  appeals.  Our  sense  of  solitude  has  disappeared. 
We  feel  that,  if  only  as  infinitesimal  atoms,  we  form  part 
of  that  immense  universe,  and  this  dumb  language  of 
the  starry  night  is  more  eloquent  than  any  speech.  Each 
star  becomes  a  friend,  a  discreet  confidant,  often  indeed 
a  precious  counsellor,  for  all  the  thoughts  it  suggests 
to  us  are  pure  and  holy. 

Is  any  poem  finer  than  the  book  written  in  let- 
ters of  fire  upon  the  tablets  of  the  firmament  ?  Noth- 
ing could  be  more  ideal.  And  yet,  the  poetic  senti- 
ment that  the  beauty  of  Heaven  awakens  in  our  soul 

12 


THE  CONTEMPLATION  OF  THE  HEAVENS 

ought  not  to  veil  its  reality  from  us.  That  is  no  less 
marvelous  than  the  mystery  by  which  we  were  en- 
chanted. 

And  here  we  may  ask  ourselves  how  many  there  are, 
even  among  thinking  human  beings,  who  ever  raise 
their  eyes  to  the  starry  heavens  ?  How  many  men  and 
women  are  sincerely,  and  with  unfeigned  curiosity, 
interested  in  these  shining  specks,  and  inaccessible 
luminaries,  and  really  desirous  of  a  better  acquaint- 
ance with  them  ? 

Seek,  talk,  ask  in  the  intercourse  of  daily  life.  You, 
who  read  these  pages,  who  already  love  the  Heavens, 
and  comprehend  them,  who  desire  to  account  for  our 
existence  in  this  world,  who  seek  to  know  what  the 
Earth  is,  and  what  Heaven — you  shall  witness  that  the 
number  of  those  inquiring  after  truth  is  so  limited  that 
no  one  dares  to  speak  of  it,  so  disgraceful  is  it  to  the 
so-called  intelligence  of  our  race.  And  yet!  the  great 
Book  of  the  Heavens  is  open  to  all  eyes.  What  pleas- 
ures await  us  in  the  study  of  the  Universe!  Nothing 
could  speak  more  eloquently  to  our  heart  and  intellect! 

Astronomy  is  the  science  par  excellence.  It  is  the 
most  beautiful  and  most  ancient  of  all,  inasmuch  as  it 
dates  back  to  the  indeterminate  times  of  highest  an- 
tiquity. Its  mission  is  not  only  to  make  us  acquainted 
with  the  innumerable  orbs  by  which  our  nights  are 

13 


ASTRONOMY   FOR   AMATEURS 

illuminated,  but  it  is,  moreover,  thanks  to  it  that  we 
know  where  and  what  we  are.  Without  it  we  should 
live  as  the  blind,  in  eternal  ignorance  of  the  very  con- 
ditions of  our  terrestrial  existence.  Without  it  we 
should  still  be  penetrated  with  the  naive  error  that  re- 
duced the  entire  Universe  to  our  minute  globule,  ma- 
king our  Humanity  the  goal  of  the  Creation,  and  should 
have  no  exact  notion  of  the  immense  reality. 

To-day,  thanks  to  the  intellectual  labor  of  so  many 
centuries,  thanks  also  to  the  immortal  genius  of  the 
men  of  science  who  have  devoted  their  lives  to  search- 
ing after  Truth — men  such  as  Copernicus,  Galileo, 
Kepler,  Newton — the  veil  of  ignorance  has  been  rent,  and 
glimpses  of  the  marvels  of  creation  are  perceptible  in 
their  splendid  truth  to  the  dazzled  eye  of  the  thinker. 

The  study  of  Astronomy  is  not,  as  many  suppose, 
the  sacrifice  of  oneself  in  a  cerebral  torture  that  oblit- 
erates all  the  beauty,  the  fascination,  and  the  grandeur 
of  the  pageant  of  Nature.  Figures,  and  naught  but  fig- 
ures, would  not  be  entertaining,  even  to  those  most 
desirous  of  instruction.  Let  the  reader  take  courage! 
We  do  not  propose  that  he  shall  decipher  the  hiero- 
glyphics of  algebra  and  geometry.  Perish  the  thought! 
For  the  rest,  figures  are  but  the  scaffolding,  the  method, 
and  do  not  exist  in  Nature. 

We  simply  beg  of  you  to  open  your  eyes,  to  see  where 


FIG.  L The  great  Book  of  the  Heavens  is  open  to  all  eyes. 


ASTRONOMY   FOR   AMATEURS 

you  are,  so  that  you  may  not  stray  from  the  path  of 
truth,  which  is  also  the  path  of  happiness.  Once  you 
have  entered  upon  it,  no  persuasion  will  be  needed  to 
make  you  persevere.  And  you  will  have  the  profound 
satisfaction  of  knowing  that  you  are  thinking  correctly, 
and  that  it  is  infinitely  better  to  be  educated  than  to  be 
ignorant.  The  reality  is  far  beyond  all  dreams,  beyond 
the  most  fantastic  imagination.  The  most  fairy-like 
transformations  of  our  theaters,  the  most  resplendent 
pageants  of  our  military  reviews,  the  most  sumptuous 
marvels  on  which  the  human  race  can  pride  itself — 
all  that  we  admire,  all  that  we  envy  on  the  Earth — 
is  as  nothing  compared  with  the  unheard-of  wonders 
scattered  through  Infinitude.  There  are  so  many  that 
one  does  not  know  how  to  see  them.  The  fascinated 
eye  would  fain  grasp  all  at  once. 

If  you  will  yield  yourselves  to  the  pleasure  of  ga- 
zing upon  the  sparkling  fires  of  Space,  you  will  never 
regret  the  moments  passed  all  too  rapidly  in  the  con- 
templation of  the  Heavens. 

Diamonds,  turquoises,  rubies,  emeralds,  all  the 
precious  stones  with  which  women  love  to  deck  them- 
selves, are  to  be  found  in  greater  perfection,  more 
beautiful,  and  more  splendid,  set  in  the  immensity  of 
Heaven  !  In  the  telescopic  field,  we  may  watch  the 
progress  of  armies  of  majestic  and  powerful  suns,  from 

16 


THE  CONTEMPLATION  OF  THE  HEAVENS 

whose  attacks  there  is  naught  to  fear.  And  these  vaga- 
bond comets  and  shooting  stars  and  stellar  nebulae, 
do  they  not  make  up  a  prodigious  panorama  ?  What 
are  our  romances  in  comparison  with  the  History  of 
Nature  ?  Soaring  toward  the  Infinite,  we  purify  our 
souls  from  all  the  baseness  of  this  world,  we  strive  to 
become  better  and  more  intelligent. 

But  in  the  first  place,  you  ask,  what  are  the  Heavens  ? 
This  vault  oppresses  us.  We  can  not  venture  to  in- 
vestigate it. 

Heaven,  we  reply,  is  no  vault,  it  is  a  limitless  im- 
mensity, inconceivable,  unfathomable,  that  surrounds 
us  on  all  sides,  and  in  the  midst  of  which  our  globe  is 
floating.  THE  HEAVENS  ARE  ALL  THAT  EXISTS,  all 
that  we  see,  and  all  that  we  do  not  see:  the  Earth  on 
which  we  are,  that  bears  us  onward  in  her  rapid 
flight;  the  Moon  that  accompanies  us,  and  sheds  her 
soft  beams  upon  our  silent  nights;  the  good  Sun  to  which 
we  owe  our  existence  ;  the  Stars,  suns  of  Infinitude ; 
in  a  word — the  whole  of  Creation. 

Yes,  our  Earth  is  an  orb  of  the  Heavens:  the  sky  is 
her  domain,  and  our  Sun,  shining  above  our  heads, 
and  fertilizing  our  seasons,  is  as  much  a  star  as  the 
pretty  sparkjing  points  that  scintillate  up  there,  in  the 
far  distance,  and  embellish  the  calm  of  our  nights 


ASTRONOMY   FOR   AMATEURS 

with  their  brilliancy.  All  are  in  the  Heavens,  you  as 
well  as  I,  for  the  Earth,  in  her  course  through  Space, 
bears  us  with  herself  into  the  depths  of  Infinitude. 

In  the  Heavens  there  is  neither  "above"  nor  "be- 
low." These  words  do  not  exist  in  celestial  speech, 
because  their  significance  is  relative  to  the  surface  of 
this  planet  only.  In  reality,  for  the  inhabitants  of  the 
Earth,  "low"  is  the  inside,  the  center  of  the  globe, 
and  "high"  is  what  is  above  our  heads,  all  round  the 
Earth.  The  Heavens  are  what  surround  us  on  all 
sides,  to  Infinity. 

The  Earth  is,  like  her  fellows,  Mercury,  Venus, 
Mars,  Jupiter,  Saturn,  Uranus,  Neptune,  one  of  the 
planets  of  the  great  solar  family. 

The  Sun,  her  father,  protects  her,  and  directs  all  her 
actions.  She,  as  the  grateful  daughter,  obeys  him 
blindly.  All  float  in  perfect  harmony  over  the  celestial 
ocean. 

But,  you  may  say,  on  what  does  the  Earth  rest  in 
her  ethereal  navigation  ? 

On  nothing.  The  Earth  turns  round  the  colossal 
Sun,  a  little  globe  of  relatively  light  weight,  isolated 
on  all  sides  in  Space,  like  a  soap-bubble  blown  by 
some  careless  child. 

Above,  below,  on  all  sides,  millions  of  similar  globes 
are  grouped  into  families,  and  form  other  systems  of 

18 


THE   CONTEMPLATION  OF  THE   HEAVENS 

worlds  revolving  round  the  numerous  and  distant  stars 
that  people  Infinitude;  suns  more  or  less  analogous  to 
that  by  which  we  are  illuminated,  and  generally  speak- 
ing of  larger  bulk,  although  our  Sun  is  a  million  times 
larger  than  our  planet. 

Among  the  ancients,  before  the  isolation  of  our 
globe  in  Space  and  the  motions  that  incessantly  alter 
its  position  were  recognized,  the  Earth  was  supposed 
to  be  the  immobile  lower  half  of  the  Universe.  The 
sky  was  regarded  as  the  upper  half.  The  ancients 
supplied  our  world  with  fantastic  supports  that  pene- 
trated to  the  Infernal  Regions.  They  could  not  admit 
the  notion  of  the  Earth's  isolation,  because  they  had  a 
false  idea  of  its  weight.  To-day,  however,  we  know 
positively  that  the  Earth  is  based  on  nothing.  The 
innumerable  journeys  accomplished  round  it  in  all 
directions  give  definite  proof  of  this.  It  is  attached  to 
nothing.  As  we  said  before,  there  is  neither  "above" 
nor  "below"  in  the  Universe.  What  we  call  "below" 
is  the  center  of  the  Earth.  For  the  rest  the  Earth 
turns  upon  its  own  axis  in  twenty-four  hours.  Night 
is  only  a  partial  phenomenon,  due  to  the  rotary  motion 
of  the  planet,  a  motion  that  could  not  exist  under  con- 
ditions other  than  that  of  the  absolute  isolation  of  our 
globe  in  space. 

Since  the  Sun  can  only  illuminate  one  side  of  our 
3  19 


ASTRONOMY   FOR   AMATEURS 

globe  at  one  moment,  that  is  to  say  one  hemisphere, 
it  follows  that  Night  is  nothing  but  the  state  of  the 
part  that  is  not  illuminated.  As  the  Earth  revolves 
upon  itself,  all  the  parts  successively  exposed  to  the 


FIG.  2. — The  earth  in  space.     June  solstice,  midday. 

Sun  are  in  the  day,  while  the  parts  situated  opposite 
to  the  Sun,  in  the  cone  of  shadow  produced  by  the  Earth 
itself,  are  in  night.  But  whether  it  be  noon  or  mid- 
night, the  stars  always  occupy  the  same  position  in 

20 


THE  CONTEMPLATION  OF  THE   HEAVENS 

the  Heavens,  even  when,  dazzled  by  the  ardent  light 
of  the  orb  of  day,  we  can  no  longer  see  them;  and 
when  we  are  plunged  into  the  darkness  of  the  night, 
the  god  Phoebus  still  continues  to  pour  his  beneficent 
rays  upon  the  countries  turned  toward  him. 

The  sequence  of  day  and  night  is  a  phenomenon 
belonging,  properly  speaking,  to  the  Earth,  in  which 
the  rest  of  the  Universe  does  not  participate.  The 
same  occurs  for  every  world  that  is  illuminated  by  a 
sun,  and  endowed  with  a  rotary  movement.  In  abso- 
lute space,  there  is  no  succession  of  nights  and  days. 

Upheld  in  space  by  forces  that  will  be  explained  at 
a  later  point,  our  planet  glides  in  the  open  heavens 
round  our  Sun. 

Imagine  a  magnificent  aerostat,  lightly  and  rapidly 
cleaving  space.  Surround  it  with  eight  little  balloons 
of  different  sizes,  the  smallest  like  those  sold  on  the 
streets  for  children  to  play  with,  the  larger,  such  as 
are  distributed  for  a  bonus  in  large  stores.  Imagine 
this  group  sailing  through  the  air,  and  you  have  the 
system  of  our  worlds  in  miniature. 

Still,  this  is  only  an  image,  a  comparison.  The 
balloons  are  held  up  by  the  atmosphere,  in  which  they 
float  at  equilibrium.  The  Earth  is  sustained  by  nothing 
material.  What  maintains  her  in  equilibrium  is  the 
ethereal  void;  an  immaterial  force;  gravitation.  The 

21 


ASTRONOMY   FOR   AMATEURS 

Sun  attracts  her,  and  if  she  did  not  revolve,  she  would 
drop  into  him;  but  rotating  round  him,  at  a  speed  of 
107,000  kilometers  *  (about  66,000  miles)  per  hour, 
she  produces  a  centrifugal  force,  like  that  of  a  stone  in 
a  sling,  that  is  precisely  equivalent,  and  of  contrary 
sign,  to  its  gravitation  toward  the  central  orb,  and 
these  two  equilibrated  forces  keep  her  at  the  same 
medium  distance. 

This  solar  and  planetary  group  does  not  exist  solitary 
in  the  immense  void  that  extends  indefinitely  around 
us.  As  we  said  above,  each  star  that  we  admire  in  the 
depths  of  the  sky,  and  to  which  we  lift  up  our  eyes  and 
thoughts  during  the  charmed  hours  of  the  night,  is 
another  sun  burning  with  its  own  light,  the  chief  of  a 
more  or  less  numerous  family,  such  as  are  multiplied 
through  all  space  to  infinity.  Notwithstanding  the 
immense  distances  between  the  sun-stars,  Space  is  so 
vast,  and  the  number  of  these  so  great,  that  by  an 
effect  of  perspective  due  solely  to  the  distance,  appear- 
ances would  lead  us  to  believe  that  the  stars  were 
touching.  And  under  certain  telescopic  aspects,  and 
in  some  of  the  astral  photographs,  they  really  do  appear 
to  be  contiguous. 

The    Universe    is    infinite.     Space    is    limitless.     If 

*  I  kilometer  =  0.6214  mile;   100  kilometers  may  be  taken  as  6a  miles, 
i  kilogram  is  about  2.2,  Ib.j   5  kilograms  =  n  Ib. — TRANSLATOR. 

22 


THE    CONTEMPLATION   OF  THE  HEAVENS 

our  love  for  the  Heavens  should  incite  in  us  the  impulse, 
and  provide  us  with  the  means  of  undertaking  a  journey 
directed  to  the  ends  of  Heaven  as  its  goal,  we  should 
be  astonished,  on  arriving  at  the  confines  of  the  Milky 
Way,  to  see  the  grandiose  and  phenomenal  spectacle 
of  a  new  Universe  unfold  before  our  dazzled  eyes;  and 
if  in  our  mad  career  we  crossed  this  new  archipelago 
of  worlds  to  seek  the  barriers  of  Heaven  beyond  them, 
we  should  still  find  universe  eternally  succeeding  to 
universe  before  us.  Millions  of  suns  roll  on  in  tire 
immensities  of  Space.  Everywhere,  on  all  sides,  Cre- 
ation renews  itself  in  an  infinite  variety. 

According  to  all  the  probabilities,  universal  life  is 
distributed  there  as  well  as  here,  and  has  sown  the 
germ  of  intelligence  upon  those  distant  worlds  that 
we  divine  in  the  vicinity  of  the  innumerable  suns  that 
plow  the  ether,  for  everything  upon  the  Earth  tends 
to  show  that  Life  is  the  goal  of  Nature.  Burning 
foci,  inextinguishable  sources  of  warmth  and  light, 
these  various,  multi-colored  suns  shed  their  rays 
upon  the  worlds  that  belong  to  them  and  which  they 
fertilize. 

Our  globe  is  no  exception  in  the  Universe.  As  we 
have  seen,  it  is  one  of  the  celestial  orbs,  nourished, 
warmed,  lighted,  quickened  by  the  Sun,  which  in  its 
turn  again  is  but  a  star. 


ASTRONOMY   FOR   AMATEURS 

Innumerable  Worlds!  We  dream  of  them.  Who 
can  say  that  their  unknown  inhabitants  do  not  think 
of  us  in  their  turn,  and  that  Space  may  not  be  traversed 
by  waves  of  thought,  as  it  is  by  the  vibrations  of  light 
and  universal  gravitation  ?  May  not  an  immense 
solidarity,  hardly  guessed  at  by  our  imperfect  senses, 
exist  between  the  Celestial  Humanities,  our  Earth  being 
only  a  modest  planet. 

Let  us  meditate  on  this  Infinity!  Let  us  lose  no 
opportunity  of  employing  the  best  of  our  hours,  those 
of  the  silence  and  peace  of  the  bewitching  nights,  in 
contemplating,  admiring,  spelling  out  the  words  of 
the  Great  Book  of  the  Heavens.  Let  our  freed  souls 
fly  swift  and  rapt  toward  those  marvelous  countries 
where  indescribable  joys  are  prepared  for  us,  and  let 
us  do  homage  to  the  first  and  most  splendid  of  the 
sciences,  to  Astronomy,  which  diffuses  the  light  of 
Truth  within  us. 

To  poetical  souls,  the  contemplation  of  the  Heavens 
carries  thought  away  to  higher  regions  than  it  attains 
in  any  other  meditation.  Who  does  not  remember  the 
beautiful  lines  of  Victor  Hugo  in  the  Orientales  ?  Who 
has  not  heard  or  read  them  ?  The  poem  is  called 
"  Ecstasy,"  and  it  is  a  fitting  title.  The  words  are 
sometimes  set  to  music,  and  the  melody  seems  to  com- 
plete their  pure  beauty: 

24 


THE   CONTEMPLATION  OF   THE  HEAVENS 

J'etais  seul  pres  des  flots  par  une  nuit  d'etoiles. 
Pas  un  nuage  aux  cieux,  sur  les  mers  pas  de  voiles ; 
Mes  yeux  plongeaient  plus  loin  que  le  monde  reel, 
Et  les  bois  et  les  monts  et  toute  la  nature 
Semblaient  interroger,  dans  un  confus  murmure, 
Les  flots  des  mers,  les  feux  du  ciel. 

Et  les  etoiles  d'or,  legions  infinies, 

A  voix  haute,  a  voix  basse,  avec  mille  harmonics 

Disaient,  en  inclinant  leurs  couronnes  de  feu  ; 

Et  les  flots  bleus,  que  rien  ne  gouverne  et  n'arrete, 

Disaient  en  recourbant  1'ecume  de  leur  crete  : 

.      .     .     C'est  le  Seigneur,  le  Seigneur  Dicu  ! 

Note:  Free   Translation 
1  was  alone  on  the  waves,  on  a  starry  night, 
Not  a  cloud  in  the  sky,  not  a  sail  in  sight, 
My  eyes  pierced  beyond  the  natural  world     .      .      . 
And  the  woods,  and  the  hills,  and  the  voice  of  Nature 
Seemed  to  question  in  a  confused  murmur, 

The  waves  of  the  Sea,  and  Heaven's  fires. 

And  the  golden  stars  in  infinite  legion, 
Sang  loudly,  and  softly,  in  glad  recognition, 
Inclining  their  crowns  of  fire  ; 
And  the  waves  that  naught  can  check  nor  arrest 
Sang,  bowing  the  foam  of  their  haughty  crest     «      . 
Behold  the  Lord  God— Jehovah  ! 

25 


ASTRONOMY   FOR   AMATEURS 

The  immortal  poet  of  France  was  an  astronomer. 
The  author  more  than  once  had  the  honor  of  conversing 
with  him  on  the  problems  of  the  starry  sky — and  re- 
flected that  astronomers  might  well  be  poets. 

It  is  indeed  difficult  to  resist  a  sense  of  profound 
emotion  before  the  abysses  of  infinite  Space,  when  we 
behold  the  innumerable  multitude  of  worlds  suspended 
above  our  heads.  We  feel  in  this  solitary  contempla- 
tion of  the  Heavens  that  there  is  more  in  the  Universe 
than  tangible  and  visible  matter:  that  there  are  forces, 
laws,  destinies.  Our  ants'  brains  may  know  them- 
selves microscopic,  and  yet  recognize  that  there  is  some- 
thing greater  than  the  Earth,  the  Heavens; — more 
absolute  than  the  Visible,  the  Invisible; — beyond  the 
more  or  less  vulgar  affairs  of  life,  the  sense  of  the  True, 
the  Good,  the  Beautiful.  We  feel  that  an  immense 
mystery  broods  over  Nature,— over  Being,  over  created 
things.  And  it  is  here  again  that  Astronomy  surpasses 
all  the  other  sciences,  that  it  becomes  our  sovereign 
teacher,  that  it  is  the  pharos  of  modern  philosophy. 

O  Night,  mysterious,  sublime,  and  infinite!  with- 
drawing from  our  eyes  the  veil  spread  above  us  by  the 
light  of  day,  giving  back  transparency  to  the  Heavens, 
showing  us  the  prodigious  reality,  the  shining  casket 
of  the  celestial  diamonds,  the  innumerable  stars  that 
succeed  each  other  interminably  in  immeasurable  space! 

26 


THE  CONTEMPLATION   OF   THE  HEAVENS 

Without  Night  we  should  know  nothing.  Without  it 
our  eyes  would  never  have  divined  the  sidereal  popula- 
tion, our  intellects  would  never  have  pierced  the  harmony 
of  the  Heavens,  and  we  should  have  remained  the  blind, 
deaf  parasites  of  a  world  isolated  from  the  rest  of  the 
universe.  O  Sacred  Night!  If  on  the  one  hand  it 
rests  upon  the  heights  of  Truth  beyond  the  day's  illu- 
sions, on  the  other  its  invisible  urns  pour  down  a  silent 
and  tranquil  peace,  a  penetrating  calm,  upon  our  souls 
that  weary  of  Life's  fever.  It  makes  us  forget  the 
struggles,  perfidies,  intrigues,  the  miseries  of  the  hours 
of  toil  and  noisy  activity,  all  the  conventionalities  of 
civilization.  Its  domain  is  that  of  rest  and  dreams. 
We  love  it  for  its  peace  and  calm  tranquillity.  We  love 
it  because  it  is  true.  We  love  it  because  it  places  us  in 
communication  with  the  other  worlds,  because  it  gives 
us  the  presage  of  Life,  Universal  and  Eternal,  because 
it  brings  us  Hope,  because  it  proclaims  us  citizens  of 
Heaven. 


CHAPTER   II 
THE   CONSTELLATIONS 

IN  Chapter  I  we  saw  the  Earth  hanging  in  space,  like 
a  globe  isolated  on  all  sides,  and  surrounded  at  vast 
distances  by  a  multitude  of  stars. 

These  fiery  orbs  are  suns  like  that  which  illuminates 
ourselves.  They  shine  by  their  own  light.  We  know 
this  for  a  fact,  because  they  are  so  far  off  that  they 
could  neither  be  illuminated  by  the  Sun,  nor,  still  more, 
reflect  his  rays  back  upon  us:  and  because,  on  the  other 
hand,  we  have  been  able  to  measure  and  analyze  their 
light,  Many  of  these  distant  suns  are  simple  and 
isolated;  others  are  double,  triple,  or  multiple;  others 
appear  to  be  the  centers  of  systems  analogous  to  that 
which  gravitates  round  our  own  Sun,  and  of  which  we 
form  part.  But  these  celestial  tribes  are  situated  at 
such  remote  distances  from  us  that  it  is  impossible  to 
distinguish  all  the  individuals  of  each  particular  family. 
The  most  delicate  observations  have  only  revealed  a 
few  of  them.  We  must  content  ourselves  here  with 
admiring  the  principals, — the  sun-stars, — prodigious 

28 


THE   CONSTELLATIONS 

globes,  flaming  torches,  scattered  profusely  through  the 
firmament. 

How,  then,  is  one  to  distinguish  them  ?  How  can 
they  be  readily  found  and  named  ?  There  are  so  many 
of  them! 

Do  not  fear;  it  is  quite  a  simple  matter.  In  study- 
ing the  surface  of  the  Earth  we  make  use  of  geographical 
maps  on  which  the  continents  and  seas  of  which  it 
consists  are  drawn  with  the  utmost  care.  Each  country 
of  our  planet  is  subdivided  into  states,  each  of  which 
has  its  proper  name.  We  shall  pursue  the  same  plan 
in  regard  to  the  Heavens,  and  it  will  be  all  the  easier 
since  the  Great  Book  of  the  Firmament  is  constantly 
open  to  our  gaze.  Our  globe,  moreover,  actually  re- 
volves upon  itself  so  that  we  read  the  whole  in  due 
sequence.  Given  a  clear  atmosphere,  and  a  little 
stimulus  to  the  will  from  our  love  of  truth  and  science, 
and  the  geography  of  the  Heavens,  or  "uranography," 
will  soon  be  as  familiar  to  us  as  the  geography  of  our 
terrestrial  atom. 

On  a  beautiful  summer's  night,  when  we  look  to- 
ward the  starry  sky,  we  are  at  first  aware  only  of  a  number 
of  shining  specks.  The  stars  seem  to  be  scattered 
almost  accidentally  through  Space;  they  are  so  numer- 
ous and  so  close  to  one  another  that  it  would  appear 
rash  to  attempt  to  name  them  separately.  Yet  some 

29 


ASTRONOMY   FOR   AMATEURS 

of  the  brighter  ones  particularly  attract  and  excite  our 
attention.  After  a  little  observation  we  notice  a  certain 
regularity  in  the  arrangement  of  these  distant  suns, 
and  take  pleasure  in  drawing  imaginary  figures  round 
the  celestial  groups. 

That  is  what  the  ancients  did  from  a  practical  point 
of  view.  In  order  to  guide  themselves  across  the  track- 
less ocean,  the  earliest  Phenician  navigators  noted  cer- 
tain fixed  bearings  in  the  sky,  by  which  they  mapped 
out  their  routes.  In  this  way  they  discovered  the  posi- 
tion of  the  immovable  Pole,  and  acquired  empire  over 
the  sea.  The  Chaldean  pastors,  too,  the  nomad  people 
of  the  East,  invoked  the  Heavens  to  assist  in  their 
migrations.  They  grouped  the  more  brilliant  of  the 
stars  into  Constellations  with  simple  outlines,  and  gave 
to  each  of  these  celestial  provinces  a  name  derived  from 
mythology,  history,  or  from  the  natural  kingdoms. 
It  is  impossible  to  determine  the  exact  epoch  of  this 
primitive  celestial  geography.  The  Centaur  Chiron, 
Jason's  tutor,  was  reputed  the  first  to  divide  the  Heavens 
upon  the  sphere  of  the  Argonauts.  But  this  origin  is 
a  little  mythical!  In  the  Bible  we  have  the  Prophet 
Job,  who  names  Orion,  the  Pleiades,  and  the  Hyades, 
3,300  years  ago.  The  Babylonian  Tables,  and  the 
hieroglyphs  of  Egypt,  witness  to  an  astronomy  that 
had  made  considerable  advance  even  in  those  re- 

30 


THE   CONSTELLATIONS 

mote  epochs.  Our  actual  constellations,  which  are 
doubtless  of  Babylonian  origin,  appear  to  have  been 
arranged  in  their  present  form  by  the  learned  philoso- 
pher Eudoxus  of  Cnidus,  about  the  year  360  B.C. 
Aratus  sang  of  them  in  a  didactic  poem  toward  270. 
Hipparchus  of  Rhodes  was  the  first  to  note  the  astro- 
nomical positions  with  any  precision,  one  hundred  and 
thirty  years  before  our  era.  He  classified  the  stars  in 
order  of  magnitude,  according  to  their  apparent  bright- 
ness; and  his  catalogue,  preserved  in  the  Almagest  of 
Ptolemy,  contains  1,122  stars  distributed  into  forty- 
eight  Constellations. 

The  figures  of  the  constellations,  taken  almost  en- 
tirely from  fable,  are  visible  only  to  the  eyes  of  the 
imagination,  and  where  the  ancients  placed  such  and 
such  a  person  or  animal,  we  may  see,  with  a  little  good- 
will, anything  we  choose  to  fancy.  There  is  nothing 
real  about  these  figures.  And  yet  it  is  indispensable 
to  be  able  to  recognize  the  constellations  in  order  to 
find  our  way  among  the  innumerable  army  of  the  stars, 
and  we  shall  commence  this  study  with  the  description 
of  the  most  popular  and  best  known  of  them  all,  the 
one  that  circles  every  night  through  our  Northern 
Heavens.  Needless  to  name  it;  it  is  familiar  to  every 
one.  You  have  already  exclaimed — the  Great  Bear! 

This  vast  and  splendid  association  of  suns,  which  is 

31 


ASTRONOMY   FOR  AMATEURS 

also  known  as  the  Chariot  of  David,  the  Plow  or 
Charles's  Wain,  and  the  Dipper,  is  one  of  the  finest 
constellations  in  the  Heavens,  and  one  of  the  oldest — 
seeing  that  the  Chinese  hailed  it  as  the  divinity  of  the 
North,  over  three  thousand  years  ago. 

If  any  of  my  readers  should  happen  to  forget  its 
position  in  the  sky,  the  following  is  a  very  simple  ex- 
pedient for  finding  it.  Turn  to  the  North — that  is, 
opposite  to  the  point  where  the  sun  is  to  be  found  at 
midday.  Whatever  the  season  of  the  year,  day  of  the 
month,  or  hour  of  the  night,  you  will  always  see,  high 
up  in  the  firmament,  seven  magnificent  stars,  arranged 
in  a  quadrilateral,  followed  by  a  tail,  or  handle,  of  three 
stars.  This  magnificent  constellation  never  sinks  be- 
low our  horizon.  Night  and  day  it  watches  above  us, 
turning  in  twenty-four  hours  round  a  very  famous  star 
that  we  shall  shortly  become  acquainted  with.  In  the 
figure  of  the  Great  Bear,  the  four  stars  of  the  quadri- 
lateral are  found  in  the  body,  and  the  three  at  the  ex- 
tremity make  the  tail.  As  David's  Chariot,  the  four 
stars  represent  the  wheels,  and  the  three  others  the 
horses. 

Sometimes  our  ancestors  called  them  the  Seven 
Oxen,  the  "oxen  of  the  celestial  pastures,"  from 
which  the  word  septentrion  (septem  triones,  seven  oxen 
of  labor)  is  derived.  Some  see  a  Plowshare;  others 

32 


THE   CONSTELLATIONS 

more  familiarly  call  this  figure  the  Dipper.  As  it 
rotates  round  the  pole,  its  outline  varies  with  the  differ- 
ent positions. 

It  is  not  easy  to  guess  why  this  constellation  should 
have  been  called  the  Bear.  Yet  the  name  has  had  a 
certain  influence.  From  the  Greek  word  antos  (bear) 
has  come  arctic,  and  for  its  antithesis,  antarctic.  From 
the  Latin  word  trio  (ox  of  labor)  has  come  septen- 
trion,  the  seven  oxen.  Etymology  is  not  always  logical. 
Is  not  the  word  "venerate  "derived  from  Venus  ? 

In  order  to  distinguish  one  star  from  another,  the 
convention  of  denoting  them  by  the  letters  of  the  Greek 
Alphabet  has  been  adopted,  for  it  would  be  impossible 
to  give  a  name  to  each,  so  considerable  is  their  number.* 

a  and  0  denote  the  front  wheels  of  the  Chariot 
generally  known  as  the  "  pointers;"  7  and  5  the  hind 
wheels;  e,  f,  77  the  three  horses.  All  these  stars  are 
of  the  second  order  of  magnitude  (the  specific  mean- 
ing of  this  expression  will  be  explained  in  the  next 
chapter),  except  the  last  (S)  of  the  quadrilateral,  which 
is  of  the  third  order. 

*It  is  useful  to  know  the  letters  of  the  Greek  Alphabet.  They  are  easily 
learned,  as  follows  : 


a  Alpha 

•n  Eta 

v  Nu 

T  Tau 

/9  Beta 

6  Theta 

1  Xi 

u  Upsil 

7  Gamma 

t    Iota 

o   Omicron 

(/>  Phi 

5  Delta 

K  Kappa 

TT  Pi 

xchi 

(   Epsilon 

\  Lambda 

p   Rho 

^  Psi 

<  Zeta 

fj.  Mu 

(T  or  j  Sigma 

of  Ome 

33 


ASTRONOMY   FOR   AMATEURS 

Figure  3  gives  the  outline  of  this  primitive  constella- 
tion. In  revolving  in  twenty-four  hours  round  the  Pole, 
which  is  situated  at  the  prolongation  of  a  line  drawn 
from  /3  to  a,  it  occupies  every  conceivable  position, — 
as  if  this  page  were  turned  in  all  directions.  But 
the  relative  arrangement  of  the  seven  stars  remains 
unaltered.  In  contemplating  these  seven  stars  it  must 


FIG.  3. — The  Great  Bear  (or  Dipper),  and  the  Pole-Star. 

never  be  forgotten  that  each  is  a  dazzling  sun,  a  center 
of  force  and  life.  One  of  them  is  especially  remarkable: 
£,  known  as  Mizar  to  the  Arabs.  Those  who  have  good 
sight  will  distinguish  near  it  a  minute  star,  Alcor,  or 
the  Cavalier,  also  called  Saidak  by  the  Arabs — that  is, 
the  Test,  because  it  can  be  used  as  a  test  of  vision.  But 
further,  if  you  have  a  small  telescope  at  your  disposal, 
direct  it  upon  the  fine  star  Mizar:  you  will  be  astonished 

34 


THE   CONSTELLATIONS 

at  discovering  two  of  the  finest  diamonds  you  could  wish 
to  see,  with  which  no  brilliant  is  comparable.  There 
are  several  double  stars;  these  we  shall  become  ac- 
quainted with  later  on. 

Meantime,  we  must  not  forget  our  celestial  geography. 
The  Great  Bear  will  help  us  to  find  all  the  adjacent  con- 
stellations. 

If  a  straight  line  is  drawn  (Fig.  4)  from  &  through  <x, 
which  forms  the  extremity  of  the  square,  and  is   pro- 
longed  by  a  quantity  equal   to  the  distance  of  a  from 
the  tip  of  the  handle,  we  come  on  a  star  of  second 
magnitude,       which          £9 
marks    the    extremity         $    ^ 
of   a   figure    perfectly         •    Jfc 
comparable   with    the      §  rf£ 

r.jy"'*    i 

Great  Bear,  but  small-         \     \  «      Wl 

\     \                         ***.•&    ^ 
er,  less   brilliant,  and       #fc~ ^P- • ^AV 

.     .        .        ,  ***** 

pointing    in    the   con-       FJG    ^_TQ  find  the  Pole.Star> 

trary  direction.     This 

is  the  Little  Bear,  composed,  like  its  big  brother,  of 
seven  stars;  the  one  situated  at  the  end  of  the  line  by 
which  we  have  found  it  is  the  Pole-Star. 

Immovable  in  the  region  of  the  North  Pole,  the 
Pole-Star  has  captivated  all  eyes  by  its  position  in  the 
firmament.  It  is  the  providence  of  mariners  who  have 
gone  astray  on  the  ocean,  for  it  points  them  to  the 

4  35 


ASTRONOMY   FOR   AMATEURS 

North,  while  it  is  the  pivot  of  the  immense  rotation 
accomplished  round  it  by  all  the  stars  in  twenty-four 
hours.  Hence  it  is  a  very  important  factor,  and  we 
must  hasten  to  find  it,  and  render  it  due  homage.  It 
should  be  added  that  its  special  immobility,  in  the 
prolongation  of  the  Earth's  axis,  is  merely  an  effect 
caused  by  the  diurnal  movements  of  our  planet.  Our 
readers  are  of  course  aware  that  it  is  the  earth  that 
turns  and  not  the  sky.  But  evidence  of  this  will  be 
given  later  on.  In  looking  at  the  Pole-Star,  the  South 
is  behind  one,  the  East  to  the  right,  and  the  West  to 
the  left. 

Between  the  Great  and  the  Little  Bear,  we  can 
distinguish  a  winding  procession  of  smaller  stars. 
These  constitute  the  Dragon. 

We  will  continue  our  journey  by  way  of  Cassiopeia, 
a  fine  constellation  placed  on  the  opposite  side  of  the 
Pole-Star  in  relation  to  the  Great  Bear,  and  shaped 
somewhat  like  the  open  limbs  of  the  letter  "W.  It  is 
also  called  the  Chair.  And,  in  fact,  when  the  figure 
is  represented  with  the  line  a  ft  below,  the  line  x  7  forms 
the  seat,  and  7  8  6  its  back. 

If  a  straight  line  is  drawn  from  S  of  the  Great  Bear, 
and  prolonged  beyond  the  Pole-Star  in  a  quantity  equal 
to  the  distance  which  separates  these  two  stars,  it  is 
easy  to  find  this  constellation  (Fig.  5).  This  group, 

36 


THE  CONSTELLATIONS 

like  the   preceding,  never  sets,   and   is   always   visible, 
opposite  to   the   Great   Bear.     It   revolves   in   *wenty- 


FIG.  5. — To  find  Cassiopeia. 

four  hours  round  the  Pole-Star,  and  is  to  be  seen,  now 
above,  now  below,  now  to  the  right,  now  to  the  left. 

If  in  the  next  place,  starting  from  the   stars  a  and  3 
in  the  Great  Bear,  we  draw  two  lines  which  join  at 

Square  of  Pegasus 


f- * 


Pole  Star  '%+''  '  *'"~  """?*& -* 

.       -••&(£  /  "• 

&n 


FIG.  6. — To  find  Pegasus  and  Andromeda. 

Polaris    and    are    prolonged    beyond    Cassiopeia,    we 
arrive  at  the  Square  of  Pegasus  (Fig.  6),  a  vast  con- 

37 


ASTRONOMY   FOR    AMATEURS 

stellation  that  terminates  on  one  side  in  a  prolongation 
formed  of  three  stars. 

These  three  last  stars  belong  to  Andromeda,  and 
themselves  abut  on  Perseus.  The  last  star  in  the 
Square  of  Pegasus  is  also  the  first  in  Andromeda. 

7  of  Andromeda  is  a  magnificent  double  orb,  to 
which  we  shall  return  in  the  next  chapter,  /.  *.,  the 
telescope  resolves  it  into  two  marvelous  suns,  one  of 
which  is  topaz-yellow,  and  the  other  emerald-green. 
Three  stars,  indeed,  are  visible  with  more  powerful 
instruments. 

Above  ft  and  near  a  small  star,  is  visible  a  faint, 
whitish,  luminous  trail:  this  is  the  oblong  nebula  of 
Andromeda,  the  first  mentioned  "r« 


&  -V        tne  mstory  °f  astronomy,  and  one 
/  of  the  most  beautiful  in  the  Heav- 


ens,  perceptible  to  the  unaided  eye 
on  very  clear  nights. 

The  stars  a,  ft  and  7  of  Per- 
seus    form  a  concave    bow  which 
FIG.  7.  —  Perseus,  the  wiH   serve    in    a    new   orientation. 
Pleiades,  Capella.       Jf  k  .g  prolonged  ;n  the  direction 

of  S,  we  find  a  very  brilliant  star  of  the  first  magnitude. 
This  is  Capella,  the  Goat,  in  the  constellation  of  the 
Charioteer  (Fig.  7). 

If  coming    back  to  B  in    Perseus,  a  line  is  drawn 

38 


THE   CONSTELLATIONS 

toward  the  South,  we  reach  the  Pleiades,  a  gorgeous 
cluster  of  stars,  scintillating  like  the  finest  dust  of  dia- 
monds, on  the  shoulder  of  the  Bull,  to  which  we  shall 
come  shortly,  in  studying  the  Constellations  of  the 
Zodiac. 

Not  far  off  is  a  very  curious  star,  ft  of  Perseus,  or 
Algol,  which  forms  a  little  triangle  with  two  others 
smaller  than  itself.  This  star  is  peculiar  in  that,  in- 
stead of  shining  with  a  fixed  light,  it  varies  in  intensity, 
and  is  sometimes  pale,  sometimes  brilliant.  It  belongs 
to  the  category  of  variable  stars  which  we  shall  study 
later  on.  All  the  observations  made  on  it  for  more  than 
two  hundred  years  go  to  prove  that  a  dark  star  revolves 
round  this  sun,  almost  in  the  plane  of  our  line  of  sight, 
producing  as  it  passes  in  front  of  it  a  partial  eclipse 
that  reduces  it  from  the  second  to  the  fourth  magni- 
tude, every  other  two  days,  twenty  hours,  and  forty- 
nine  minutes. 

And  now,  let  us  return  to  the  Great  Bear,  which 
aided  us  so  beneficently  to  start  for  these  distant  shores, 
and  whence  we  shall  set  out  afresh  in  search  of  other 
constellations. 

If  we  produce  the  curved  line  of  the  tail,  or  handle, 
we  encounter  a  magnificent  golden-yellow  star,  a  splen- 
did sun  of  dazzling  brilliancy:  let  us  make  our  bow  to 
Arcturus,  a  of  the  Herdsman,  which  is  at  the  extremity 

39 


ASTRONOMY    FOR    AMATEURS 

of  this  pentagonal  constellation.  The  principal  stars 
of  this  asterism  are  of  the  third  magnitude,  with  the 
exception  of  a,  which  is  of  the  first.  Alongside  of 
the  Herdsman  is  a  circle  consisting  of  five  stars  of 
the  third  and  fourth  magnitude,  save  the  third,  a,  or  the 
Pearl,  which  is  of  the  second  magnitude.  This  is  the 
Corona  Borealis.  It  is  very  easily  recognized  (Fig.  8). 
A  line  drawn  from  the  Pole-Star  to  Arcturus 


l   Northern 
£  +     Crown 

J*      jPjfc—^P  .     Great  Pern' 


14  //'  V-1 

,/  '       P 


rcturus 

FIG.  8.  —  To  find  Arcturus,  the  Herdsman,  and  the  Northern 
Crown. 

forms  the  base  of  an  equilateral  triangle,  the  apex  of 
which,  situated  opposite  the  Great  Bear,  is  occupied 
by  Vega,  or  a  of  the  Lyre,  a  splendid  diamond  of  ideal 
purity  scintillating  through  the  ether.  This  magnificent 
star,  of  first  magnitude,  is,  with  Arcturus,  the  most  lumi- 
nous in  our  Heavens.  It  burns  with  a  white  light,  in  the 
proximity  of  the  Milky  Way,  not  far  from  a  constella- 
tion that  is  very  easily  recognized  by  the  arrangement 
of  its  principal  stars  in  the  form  of  a  cross.  It  is  named 
Cygnus,  the  Bird,  or  the  Swan  (Fig.  9),  and  is 

40 


THE   CONSTELLATIONS 

easy  to  find  by  the  Square  of  Pegasus,  and  the  Milky 
Way.  This  figure,  the  brilliancy  of  whose  constituents 
(of  the  third  and  fourth  magnitudes)  contrasts  strongly 
with  the  pallor  of  the  Milky  Way,  includes  at  its  ex- 
tremity at  the  foot  of  the  Cross,  a  superb  double  star, 
/3  or  Albirio  :  a  of  Cygnus  is  also  called  Deneb. 
The  first  star  of  which  the  distance  was  calculated  is 
in  this  constellation.  This  little  orb  of  fifth  magnitude, 

,*'  V*. 


.  Square  of  Pegasus  x     . 


*/? 

FIG.  9. — The  Swan,  Vega,  the  Eagle. 

which  hangs  69,000,000,000,000  kilometers  (42,000,- 
000,000,000  miles)  above  our  Earth,  is  the  nearest  of 
all  the  stars  to  the  skies  of  Europe. 

Not  far  off  is  the  fine  Eagle,  which  spreads  its  wings 
in  the  Milky  Way,  and  in  which  the  star  Altair,  a,  of 
first  magnitude,  is  situated  between  its  two  satellites* 
@  and  7. 

The  Constellation  of  Hercules,  toward  which  the 
41 


ASTRONOMY    FOR    AMATEURS 

motions  of  the  Sun  are  impelling  us,  with  all  the  planets 
of  its  system,  is  near  the  Lyre.  Its  principal  stars  can 
be  recognized  inside  the  triangle  formed  by  the  Pole- 
Star,  Arcturus,  and  Vega. 

All  the  Constellations  described  above  belong  to  the 
Northern  Hemisphere.  Those  nearest  the  pole  are  called 
circumpolar.  They  revolve  round  the  pole  in  twenty- 
four  hours. 

Having  now  learned  the  Northern  Heavens,  we 
must  come  back  to  the  Sun,  which  we  have  left  behind 
us.  The  Earth  revolves  round  him  in  a  year,  and 
in  consequence  he  seems  to  revolve  round  us,  sweeping 
through  a  vast  circle  of  the  celestial  sphere.  In  each 
year,  at  the  same  period,  he  passes  the  same  points  of  the 
Heavens,  in  front  of  the  same  constellations,  which 
are  rendered  invisible  by  his  light.  We  know  that  the 
stars  are  at  a  fixed  position  from  the  Earth,  whatever 
their  distance,  and  that  if  we  do  not  see  them  at  noon 
as  at  midnight,  it  is  simply  because  they  are  extin- 
guished by  the  dazzling  light  of  the  orb  of  day.  With 
the  aid  of  a  telescope  it  is  always  possible  to  see  the 
more  brilliant  of  them. 

The  Zodiac  is  the  zone  of  stars  traversed  by  the  Sun 
in  the  course  of  a  year.  This  word  is  derived  from  the 
Greek  7<odiakos,  which  signifies  "  animal, "  and  this 
etymology  arose  because  most  of  the  figures  traced 

42 


THE   CONSTELLATIONS 

on  this  belt  of  stars  represent  animals.  The  belt  is 
divided  into  twelve  parts  that  are  called  the  twelve 
Signs  of  the  Zodiac,  also  named  by  the  ancients  the 
"Houses  of  the  Sun,"  since  the  Sun  visits  one  of  them 
in  each  month.  These  are  the  signs,  with  the  primitive 
characters  that  distinguish  them:  the  Ram  T,  the 
Bull  8  ,  the  Twins  n,  the  Crab  gs,  the  Lion  SI,  the 
Virgin  TT#,  the  Balance  ===,  the  Scorpion  TH, .  the  Archer  f  , 
the  Goat  V3,  the  Water-Carrier  £?,  the  Fishes  X.  The 
sign  T  represents  the  horns  of  the  Ram,  tf  the  head  of 
the  Bull,  and  so  on. 

If  you  will  now  follow  me  into  the  Houses  of  the  Sun 
you  will  readily  recognize  them  again,  provided  you 
have  a  clear  picture  of  the  principal  stars  of  the  North- 
ern Heavens.  First,  you  see  the  Ram,  the  initial  sign 
of  the  Zodiac;  because  at  the  epoch  at  which  the  actual 
Zodiac  was  fixed,  the  Sun  entered  this  sign  at  the  vernal 
equinox,  and  the  equator  crossed  the  ecliptic  at  this 
point.  This  constellation,  in  which  the  horns  of  the 
Ram  (third  magnitude)  are  the  brightest,  is  situated 
between  Andromeda  and  the  Pleiades.  Two  thousand 
years  ago,  the  Ram  was  regarded  as  the  symbol  of 
spring  ;  but  owing  to  the  secular  movement  of  the  pre- 
cession of  the  equinoxes,  the  Sun  is  no  longer  there  on 
March  21 :  he  is  in  the  Fishes. 

To  the  left,  or  east  of  the  Ram,  we  find  the  Bull, 

43 


ASTRONOMY   FOR   AMATEURS 

the  head  of  which  forms  a  triangle  in  which  burns 
Aldebaran,  of  first  magnitude,  a  magnificent  red  star 
that  marks  the  right  eye;  and  the  Hyades,  scintillat- 
ing pale  and  trembling,  on  its  forehead.  The  timid 
Pleiades,  as  we  have  seen,  veil  themselves  on  the  shoul- 
der of  the  Bull — a  captivating  cluster,  of  which  six  stars 
can  be  counted  with  the  unaided  eye,  while  several 
hundred  are  discovered  with  the  telescope. 

Next  the  Twins.  They  are  easily  recognized  by 
the  two  fine  stars,  a  and  /3,  of  first  magnitude,  which 
mark  their  heads,  and  immortalize  Castor  and  Pollux, 
the  sons  of  Jupiter,  celebrated  for  their  indissoluble 
friendship. 

Cancer,  the  Crab,  is  the  least  important  sign  of  the 
Zodiac.  It  is  distinguished  only  by  five  stars  of  fourth 
and  fifth  magnitudes,  situated  below  the  line  of  Castor 
and  Pollux,  and  by  a  pale  cluster  called  Praesepe,  the 
Beehive. 

The  Lion  next  approaches,  superb  in  his  majesty. 
At  his  heart  is  a  gorgeous  star  of  first  magnitude,  a  or 
Regulus.  This  figure  forms  a  grand  trapezium  of  four 
stars  on  the  celestial  sphere. 

The  Virgin  exhibits  a  splendid  star  of  first  magnitude; 
this  is  Spica,  which  with  Regulus  and  Arcturus,  form 
a  triangle  by  which  this  constellation  can  be  recog- 
nized. 

44 


THE  CONSTELLATIONS 

The  Balance  follows  the  Virgin.  Its  scales,  marked 
by  two  stars  of  second  magnitude,  are  situated  a  little 
to  the  East  of  Spica. 

We  next  come  to  the  eighth  constellation  of  the 
Zodiac,  which  is  one  of  the  most  beautiful  of  this  belt 
of  stars.  Antares,  a  red  star  of  first  magnitude,  occupies 
the  heart  of  the  venomous  and  accursed  Scorpion.  It 
is  situated  on  the  prolongation  of  a  line  joining  Regulus 
to  Spica,  and  forms  with  Vega  of  the  Lyre,  and  Arcturus 
of  the  Herdsman,  a  great  isosceles  triangle,  of  which 
this  latter  star  is  the  apex. 

The  Scorpion,  held  to  be  a  sign  of  ill  luck,  has  been 
prejudicial  to  the  Archer,  which  follows  it,  and  traces 
an  oblique  trapezium  in  the  sky,  a  little  to  the  east  of 
Antares.  These  two  southernmost  constellations  never 
rise  much  above  the  horizon  for  France  and  England. 
In  fable,  the  Archer  is  Chiron,  the  preceptor  of  Jason, 
Achilles  and  /Esculapius. 

Capricorn  lies  to  the  south  of  Altair,  on  the  pro- 
longation of  a  line  from  the  Lyre  to  the  Eagle.  It  is 
hardly  noticeable  save  for  the  stars  a  and  ft  of  third 
magnitude,  which  scintillate  on  its  forehead. 

The  Water-Carrier  pours  his  streams  toward  the 
horizon.  He  is  not  rich  in  stars,  exhibiting  only  three 
of  third  magnitude  that  form  a  very  flattened  triangle. 

Lastly  the  Fishes,  concluding  sign  of  the  Zodiac,  are 

45 


ASTRONOMY   FOR   AMATEURS 

found  to  the  south  of  Andromeda  and  Pegasus.  Save 
for  a,  of  third  magnitude,  this  constellation  consists 
of  small  stars  that  are  hardly  visible. 

These  twelve  zodiacal  constellations  will  be  recog- 
nized on  examining  the  chart  (Figs.  10-11). 

We  must  now  visit  the  stars  of  the  Southern  Heav- 
ens, some  of  which  are  equally  deserving  of  admiration. 

It  should  in  the  first  place  be  noted  that  the  signs 


•*              *     *    *            * 

SERPENS             >|     &Arctlirus 

**               *              * 

+  *                         BOOTES 

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^^^-^                 VIRGO                  *         W               * 

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CAPRICORNUS^ 

Ecliptic          * 

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V            Antares  $ 

6AGITTAffiuSji_                  SCORPIO 

*         *                                               ^^^^^j- 

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»                   Jt                                                                      HYDRA  ^ 
CENTAUR08                                                    •*• 

FIG.    10. — The  Constellations  of  the  Zodiac:     summer    and    autumn; 
Capricorn,  Archer,  Scorpion,  Balance,  Virgin,  Lion. 

of  the  Zodiac  and  the  Southern  Constellations  are  not, 
like  those  which  are  circumpolar,  perpetually  visible 
at  all  periods  of  the  year.  Their  visibility  depends  on 
the  time  of  year  and  the  hour  of  the  night.* 

In  order  to    admire   the   fine  constellations   of  the 
North,  as  described  above,  we  have  only  to  open  our 

*  All  the  stars  visible  at  any  hour  during  the  year  can  easily  be  found  with 
the  help  of  the  author's  Planisphere  mobile. 

46 


THE   CONSTELLATIONS 

windows  on  a  clear  summer's  evening,  or  walk,  round 
the  garden  in  the  mysterious  light  of  these  inaccessible 
suns,  while  we  look  up  at  the  immense  fields  in  which 
each  star  is  like  the  head  of  a  celestial  spear. 

But  the  summer  is  over,  autumn  is  upon  us,  and 
then,  too  soon,  comes  winter  clothed  in  hoarfrost. 
The  days  are  short  and  cold,  dark  and  dreary;  but  as 
a  compensation  the  night  is  much  longer,  and  adorns 


*      *     *  PEGASUS  -. 

^ANDROMEDA  Markab 


AURIGA      ^  +  •¥• 

Castor    *         M ^ ARIES -trAlgen.il 

h£~^        pBHtta:  *  GEM.N,             *                  ^Pleiades       *            PISCES               .^^UARIUS  * 
Ecliptic r,       4      TAURUS ^^^Ecliytic 

4.    Aldebaran  Iff  * 


CAMS  MINOR 


MONOCEROS  *    $  /Ji^eZ  *  ERIDAN 


*  * 

US 


Sirius-Q-   * 

FIG.  1 1 . — The  Constellations  of  the  Zodiac  :  winter  and  spring  ;  Crab, 
Twins,  Bull,  Ram,  Fishes,  Water- Carrier. 

herself  with  her  most  beautiful  jewels,  offering  us  the 
contemplation  of  her  inexhaustible  treasures. 

First,  let  us  do  homage  to  the  magnificent  Orion, 
most  splendid  of  all  the  constellations:  he  advances  like 
a  colossal  giant,  and  confronts  the  Bull. 

This  constellation  appears  about  midnight  in  No- 
vember, in  the  south-eastern  Heavens;  toward  eleven 

47 


ASTRONOMY   FOR   AMATEURS 

o'clock  in  December  and  January,  due  south;  about 
ten  in  February,  in  the  south-east;  about  nine  in  March, 
and  about  eight  in  April,  in  the  west;  and  then  sets 
below  our  horizon. 


FIG.   12. — Orion  and  his  celestial  companions. 

It  is  indisputably  the  most  striking  figure  in  the  sky, 
and  with  the  Great  Bear,  the  most  ancient  in  history, 
the  first  that  was  noticed :  both  are  referred  to  in  the  an- 
cient texts  of  China,  Chaldea,  and  Egypt. 

48 


THE    CONSTELLATIONS 

Eight  principal  stars  delineate  its  outline;  two  are  of 
the  first  magnitude,  five  of  the  second,  and  one  of  the 
third  (Fig.  12).  The  most  brilliant  are  Betelgeuse  (a)  and 
Rigel  (ft) :  the  former  marking  the  right  shoulder  of  the 
Colossus  as  it  faces  us;  the  second  the  left  foot.  The  star 
on  the  left  shoulder  is  7  or  Bellatrix,  of  second  magni- 
tude; that  of  the  right  foot,  ^,  is  almost  of  the  third. 
Three  stars  of  second  magnitude  placed  obliquely  at 
equal  distances  from  each  other,  the  first  or  highest 
of  which  marks  the  position  of  the  equatorial  line, 
indicate  the  Belt  or  Girdle.  These  stars,  known  as  the 
Three  Kings,  and  by  country  people  as  the  Rake,  as- 
sist greatly  in  the  recognition  of  this  fine  constellation. 

A  little  below  the  second  star  of  the  Belt,  a  large 
white  patch,  like  a  band  of  fog,  the  apparent  dimensions 
of  which  are  equal  to  that  of  the  lunar  disk,  is  visible 
to  the  unaided  eye:  this  is  the  Nebula  of  Orion,  one  of 
the  most  magnificent  in  the  entire  Heavens.  It  was 
discovered  in  1656  by  Huyghens,  who  counted  twelve  stars 
in  the  pale  cloud.  Since  that  date  it  has  been  constantly 
studied  and  photographed  by  its  many  admirers,  while 
the  giant  eye  of  the  telescope  discovers  in  it  to-day 
an  innumerable  multitude  of  little  stars  which  reveal 
the  existence  of  an  entire  universe  in  this  region. 

Orion  is  not  merely  the  most  imposing  of  the  celestial 
figures;  it  is  also  the  richest  in  sidereal  wonders.  Among 

49 


ASTRONOMY   FOR   AMATEURS 

these,  it  exhibits  the  most  complex  of  all  the  multiple 
systems  known  to  us :  that  of  the  star  6  situated  in  the 
celebrated  nebula  just  mentioned.  This  marvelous 
star,  viewed  through  a  powerful  telescope,  breaks  up 
into  six  suns,  forming  a  most  remarkable  stellar  group. 

This  region  is  altogether  one  of  the  most  brilliant  in 
the  entire  firmament.  We  must  no  longer  postpone  our 
homage  to  the  brightest  star  in  the  sky,  the  magnificent 
Sirius,  which  shines  on  the  left  below  Orion:  it  returns 
every  year  toward  the  end  of  November.  This  mar- 
velous star,  of  dazzling  brilliancy,  is  the  first,  a,  in  the 
constellation  of  the  Great  Dog,  which  forms  a  quadri- 
lateral, the  base  of  which  is  adjacent  to  a  triangle 
erected  from  the  horizon. 

When  astronomers  first  endeavored  to  determine  the 
distance  of  the  stars,  Sirius,  which  attracted  all  eyes 
to  its  burning  fires,  was  the  particular  object  of  attention. 
After  long  observation,  they  succeeded  in  determin- 
ing its  distance  as  92  trillion  kilometers  (57  trillion 
miles).  Light,  that  radiates  through  space  at  a  velocity 
of  300,000  kilometers  (186,000  miles)  per  second,  takes 
no  less  than  ten  years  to  reach  us  from  this  sun,  which, 
nevertheless,  is  one  of  our  neighbors. 

The  Little  Dog,  in  which  Procyon  (a,  of  first  magni- 
tude) shines  out,  is  above  its  big  brother.  With  the  ex- 
ception of  a,  it  has  no  bright  stars. 

5° 


THE    CONSTELLATIONS 

Lastly,  toward  the  southern  horizon,  we  must  notice 
the  Hydra,  Eridanus,  the  Whale,  the  Southern  Fish,  the 


Ship,   and  the  Centaur.     This  last  constellation,  while 
invisible    to    our    latitudes,  contains    the   star   that   is 

5  51 


ASTRONOMY    FOR    AMATEURS 

nearest  to   the   Earth,   #,   of  first   magnitude,   the   dis- 
tance of  which  is  40  trillion  kilometers  (25  trillion  miles). 


The  feet  of  the  Centaur  touch  the  Southern  Cross, 
which   is   always   invisible   to    us,   and   a   little   farther 


THE   CONSTELLATIONS 

down  the  Southern  Pole  reigns  over  the  icy   desert  of 
the  antarctic  regions. 


In  order  to  complete  the  preceding  descriptions,  we 
subjoin  four  charts  representing  the  aspect  of  the  starry 

S3 


ASTRONOMY  FOR  AMATEURS 

heavens  during  the  evenings  of  winter,  spring,  summer, 
and  autumn.     To  make  use  of  these,  we  must  suppose 


them  to  be  placed  above  our  heads,  the  center  marking 
the  zenith,  and  the  sky  descending  all  round  to  the  hori- 

54 


THE  CONSTELLATIONS 

zon.  The  horizon,  therefore,  bounds  these  panoramas. 
Turning  the  chart  in  any  direction,  and  looking  at  it 
from  north,  south,  east,  or  west,  we  find  all  the  prin- 
cipal stars.  The  first  map  (Fig.  13)  represents  the  sky 
in  winter  (January)  at  8  P.  M.;  the  second,  in  spring 
(April)  at  9  P.  M.;  the  third,  in  summer  (July)  at  the 
same  hour;  the  fourth,  the  sky  in  autumn  (October) 
at  the  same  time. 

And  so,  at  little  cost,  we  have  made  one  of  the  grand- 
est and  most  beautiful  journeys  conceivable.  We  now 
have  a  new  country,  or,  better,  have  learned  to  see  and 
know  our  own  country,  for  since  the  Earth  is  a  planet 
we  must  all  be  citizens  of  the  Heavens  before  we  can 
belong  to  such  or  such  a  nation  of  our  lilliputian  world. 

We  must  now  study  this  sublime  spectacle  of  the 
Heavens  in  detail. 


55 


CHAPTER  III 

THE   STARS,    SUNS    OF   THE   INFINITE 
A  JOURNEY  THROUGH  SPACE 

WE  have  seen  from  the  foregoing  summary  of  the 
principal  Constellations  that  there  is  great  diversity  in 
the  brightness  of  the  stars,  and  that  while  our  eyes  are 
dazzled  with  the  brilliancy  of  certain  orbs,  others,  on  the 
contrary,  sparkle  modestly  in  the  azure  depths  of  the 
night,  and  are  hardly  perceptible  to  the  eye  that  seeks 
to  plumb  the  abysses  of  Immensity. 

We  have  appended  the  word  "magnitude"  to  the 
names  of  certain  stars,  and  the  reader  might  imagine 
this  to  bear  some  relation  to  the  volume  of  the  orb. 
But  this  is  not  the  case. 

To  facilitate  the  observation  of  stars  of  varying  bril- 
liancy, they  have  been  classified  in  order  of  magnitude, 
according  to  their  apparent  brightness,  and  since  the 
dimensions  of  these  distant  suns  are  almost  wholly  un- 
known to  us,  the  most  luminous  stars  were  naturally 
denoted  as  of  first  magnitude,  those  which  were  a  little 
less  bright 'of  the  second,  and  so  on.  But  in  reality 

56 


THE  STARS,  SUNS  OF  THE  INFINITE 

this  word  "magnitude"  is  quite  erroneous,  for  it  bears 
no  relation  to  the  mass  of  the  stars,  divided  thus  at  an 
epoch  when  it  was  supposed  that  the  most  brilliant 
must  be  the  largest.  It  simply  indicates  the  apparent 
brightness  of  a  star,  the  real  brilliancy  depending  on  its 
dimensions,  its  intrinsic  light,  and  its  distance  from 
our  planet. 

And  now  to  make  some  comparison  between  the 
different  orders.  Throughout  the  entire  firmament, 
only  nineteen  stars  of  first  magnitude  are  discover- 
able. And,  strictly  speaking,  the  last  of  this  series 
might  just  as  well  be  noted  of  "second  magnitude," 
while  the  first  of  the  second  series  might  be  added  to 
the  list  of  stars  of  the  "first  order."  But  in  order  to 
form  classes  distinct  from  one  another,  some  limit  has 
to  be  adopted,  and  it  was  determined  that  the  first  series 
should  include  only  the  following  stars,  the  most  lumi- 
nous in  the  Heavens,  which  are  subjoined  in  order  of 
decreasing  brilliancy. 

STARS   OF   THE    FIRST   MAGNITUDE 

1.  Sirius,  or  a  of  the  Great  Dog. 

2.  Canopus,  or  a  of  the  Ship. 

3.  Capella,  or  a  of  the  Charioteer. 

4.  Arcturus,  or  a  of  the  Herdsman. 

5.  Vega,  or  a  of  the  Lyre. 

57 


ASTRONOMY  FOR    AMATEURS 

6.  Proxima,  or  a  of  the  Centaur, 

7.  Rigel,  or  ft  of  Orion. 

8.  Achernar,  or  a  of  Eridanus. 

9.  Procyon,  or  a  of  the  Little  Dog. 

10.  0  of  the  Centaur. 

11.  Betelgeuse,  or  a  of  Orion. 

12.  Altair,  or  a  of  the  Eagle. 

13.  a  of  the  Southern  Cross. 

14.  Aldebaran,  or  a  of  the  Bull. 

15.  Spica,  or  a  of  the  Virgin. 

16.  Antares,  or  a  of  the  Scorpion. 

17.  Pollux,  or  /9  of  the  Twins. 

18.  Regulus,  or  a  of  the  Lion. 

19.  Fomalhaut,  or  a  of  the  Southern  Fish. 

THE    STARS    OF   THE    SECOND    MAGNITUDE 

Then  come  the  stars  of  the  second  magnitude,  of 
which  there  are  fifty-nine.  The  stars  of  the  Great 
Bear  (with  the  exception  of  8,  which  is  of  third  magni- 
tude), the  Pole-Star,  the  chief  stars  in  Orion  (after  Rigel 
and  Betelgeuse),  of  the  Lion,  of  Pegasus,  of  Andromeda, 
of  Cassiopeia,  are  of  this  order.  These,  with  the  former, 
constitute  the  principal  outlines  of  the  constellations 
visible  to  us. 

Then  follow  the  third  and  fourth  magnitudes,  and 
so  on. 


THE  STARS,  SUNS  OF  THE  INFINITE 

The  following  table  gives  a  summary  of  the  series, 
down   to   the   sixth   magnitude,  which  is  the  limit  of 
visibility  for  the  unaided  human  eyer 
19  stars  of  first  magnitude. 
59  of  second  magnitude. 
182  of  third  magnitude. 
530  of  fourth  magnitude. 
I,6oo  of  fifth  magnitude. 
4,800  of  sixth  magnitude. 

This  makes  a  total  of  some  seven  thousand  stars 
visible  to  the  unaided  eye.  It  will  be  seen  that  each 
series  is,  roughly  speaking,  three  times  as  populated  as 
that  preceding  it;  consequently,  if  we  multiply  the  num- 
ber of  any  class  by  three,  we  obtain  the  approximate 
number  of  stars  that  make  up  the  class  succeeding  it. 

Seven  thousand  stars!  It  is  an  imposing  figure,  when 
one  reflects  that  all  these  lucid  points  are  suns,  as 
enormous  as  they  are  potent,  as  incandescent  as  our  own 
(which  exceeds  the  volume  of  the  Earth  by  more  than  a 
million  times),  distant  centers  of  light  and  heat,  exerting 
their  attraction  on  unknown  systems.  And  yet  it  is  gen- 
erally imagined  that  millions  of  stars  are  visible  in  the 
firmament.  This  is  an  illusion;  even  the  best  vision  is 
unable  to  distinguish  stars  below  the  sixth  magnitude, 
and  ordinary  sight  is  far  from  discovering  all  of  these. 
Again,  seven  thousand  stars  for  the  whole  Heavens 

59 


ASTRONOMY   FOR   AMATEURS 

makes  only  three  thousand  five  hundred  for  half  the 
sky0  And  we  can  only  see  one  celestial  hemisphere 
at  a  time.  Moreover,  toward  the  horizon,  the  vapor 
of  the  atmosphere  veils  the  little  stars  of  sixth  magni- 
tude. In  reality,  we  never  see  at  a  given  moment 
more  than  three  thousand  stars.  This  number  is  below 
that  of  the  population  of  a  small  town. 

But  celestial  space  is  unlimited,  and  we  must  not 
suppose  that  these  seven  thousand  stars  that  fascinate 
our  eyes  and  enrich  our  Heavens,  without  which  our 
nights  would  be  black,  dark,  and  empty,*  comprise 
the  whole  of  Creation.  They  only  represent  the  vesti- 
bule of  the  temple. 

Where  our  vision  is  arrested,  a  larger,  more  powerful 
eye,  that  is  developing  from  century  to  century,  plunges 
its  analyzing  gaze  into  the  abysses,  and  reflects  back 
to  the  insatiable  curiosity  of  science  the  light  of  the 
innumerable  suns  that  it  discovers.  This  eye  is  the  lens 
of  the  optical  instruments.  Even  opera-glasses  disclose 
stars  of  the  seventh  magnitude.  A  small  astronomical 
objective  penetrates  to  the  eighth  and  ninth  orders. 
More  powerful  instruments  attain  the  tenth.  The 

*  Let  it  be  remarked  in  passing  that  the  stars  might  be  much  farther  off 
than  they  are,  and  invisible  to  our  eyes  ;  the  Heavens  would  then  assume  the 
aspect  of  an  absolutely  empty  space,  the  moon  and  planets  alone  remaining. 

60 


THE  STARS,  SUNS  OF  THE  INFINITE 

Heavens  are  progressively  transformed  to  the  eye  of  the 
astronomer,  and  soon  he  is  able  to  reckon  hundreds  of 
thousands  of  orbs  in  the  night.  The  evolution  con- 
tinues, the  power  of  the  instrument  is  developed;  and 
the  stars  of  the  eleventh  and  twelfth  magnitudes  are 
discovered  successively,  and  together  number  four 
millions.  Then  follow  the  thirteenth,  fourteenth,  and 
fifteenth  magnitudes.  This  is  the  sequence: 

yth  magnitude 13,000. 

8th  40,000. 

9th  120,000. 

loth  380,000. 

nth  .- 1,000,000. 

I2th  3,000,000. 

I3th  9,000,000. 

I4th  27,000,000. 

I5th  80,000,000. 

Accordingly,  the  most  powerful  telescopes  of  the 
day,  reenforced  by  celestial  photography,  can  bring  a 
stream  of  more  than  120  millions  of  stars  into  the  scope 
of  our  vision. 

The  photographic  map  of  the  Heavens  now  being 
executed  comprises  the  first  fourteen  magnitudes,  and 
will  give  the  precise  position  of  some  40,000,000  stars, 
distributed  over  22,054  sheets,  forming  a  sphere  3 
meters  44  centimeters  in  diameter. 

6,1 


ASTRONOMY  FOR  AMATEURS 

The  boldest  imagination  is  overwhelmed  by  these 
figures,  and  fails  to  picture  such  millions  of  suns — 
formidable  and  burning  globes  that  roll  through  space, 
sweeping  their  systems  along  with  them.  What  fur- 
naces are  there!  what  unknown  lives!  what  vast  im- 
mensities! 

And  again,  what  enormous  distances  must  separate 
the  stars,  to  admit  of  their  free  revolution  in  the  ether! 
In  what  abysses,  at  what  a  distance  from  our  terrestrial 
atom,  must  these  magnificent  and  dazzling  Suns  pursue 
the  paths  traced  for  them  by  Destiny! 

If  all  the  stars  radiated  an  equal  light,  their  distances 
might  be  calculated  on  the  principle  that  an  object  ap- 
pears smaller  in  proportion  to  its  distance.  But  this 
equality  does  not  exist.  The  suns  were  not  all  cast 
in  the  same  mold. 

Indeed,  the  stars  differ  widely  in  size  and  brightness, 
and  the  distances  that  have  been  measured  show  that 
the  most  brilliant  are  not  the  nearest.  They  are  scat- 
tered through  Space  at  all  distances. 

Among  the  nearer  stars  of  which  it  has  been  found 
possible  to  calculate  the  distance,  some  are  found  to  be 
of  the  fourth,  fifth,  sixth,  seventh,  eighth,  and  even  ninth 
magnitudes,  proving  that  the  most  brilliant  are  not 
always  the  least  distant. 

62 


THE  STARS,  SUNS  OF  THE  INFINITE 

For  the  rest,  among  the  beautiful  and  shining  stars 
with  which  we  made  acquaintance  in  the  last  chapter 
may  be  cited  Sirius,  which  at  a  distance  of  92  trillion 
kilometers  (57  trillion  miles)  from  here  still  dazzles  us 
with  its  burning  fires;  Procyon  or  a  of  the  Little  Dog, 
as  remote  as  112  trillion  kilometers  (69^  trillion  miles); 
Altai'r  of  the  Eagle,  at  160  trillion  kilometers  (99  trillion 
miles);  the  white  Vega,  at  204  trillion  kilometers  (126^ 
trillion  miles);  Capella,  at  276  (171  trillion  miles); 
and  the  Pole-Star  at  344  trillion  kilometers  (213^ 
trillion  miles).  The  light  that  flies  through  Space  at 
a  velocity  of  300,000  kilometers  (186,000  miles)  per 
second,  takes  thirty-six  years  and  a  half  to  reach  us 
from  this  distant  sun:  i.  e.9  the  luminous  ray  we  are 
now  receiving  from  Polaris  has  been  traveling  for 
more  than  the  third  of  a  century.  When  you,  gentle 
reader,  were  born,  the  ray  that  arrives  to-day  from  the 
Pole-Star  was  already  speeding  on  its  way.  In  the  first 
second  after  it  had  started  it  traveled  300,000  kilo- 
meters ;  in  the  second  it  added  another  300,000  which 
at  once  makes  600,000  kilometers;  add  another  300,- 
ooo  kilometers  for  the  third  second,  and  so  on  during 
the  thirty-six  years  and  a  half. 

If  we  tried  to  arrange  the  number  300,000  (which 
represents  the  distance  accomplished  in  one  second)  in 
superposed  rows,  as  if  for  an  addition  sum,  as  many 

63 


ASTRONOMY  FOR  AMATEURS 

times  as  is  necessary  to  obtain  the  distance  that  sepa- 
rates the  Pole-Star  from  our  Earth,  the  necessary  opera- 
tion would  comprise  1,151,064,000  rows,  and  the  sheet 
of  paper  required  for  the  setting  out  of  such  a  sum 
would  measure  approximately  11,510  kilometers  (about 
7,000  miles),  /*.  ^.,  almost  the  diameter  of  our  terrestrial 
globe,  or  about  four  times  the  distance  from  Paris  to 
Moscow! 

Is  it  not  impossible  to  realize  that  our  Sun,  with  its 
entire  system,  is  lost  in  the  Heavens  at  such  a  distance 
from  his  peers  in  Space  ?  At  the  distance  of  the  least 
remote  of  the  stars  he  would  appear  as  one  of  the 
smallest. 

The  nearest  star  to  us  is  a  of  the  Centaur,  of  first 
magnitude,  a  neighbor  of  the  South  Pole,  invisible 
in  our  latitudes.  Its  distance  is  275,000  radii  of  the 
terrestrial  orbit,  I.  e.y  275,000  times  149  million  kilo- 
meters, which  gives  41  trillions,  or  41,000  milliards  of 
kilometers  (=  25^  trillion  miles).  [A  milliard  =  1,000 
millions,  the  French  billion.  A  trillion  =  1,000  mil- 
liards, or  a  million  millions,  the  English  billion.  The 
French  nomenclature  has  been  retained  by  the  trans- 
lator.] At  a  speed  of  300,000  kilometers  (186,000  miles) 
per  second  the  light  takes  four  years  to  come  from 
thence.  It  is  a  fine  double  star. 

64 


THE  STARS.  SUNS  OF  THE  INFINITE 

The  next  nearest  star  after  this  is  a  little  orb  in- 
visible to  the  unaided  eye.  It  has  no  name,  and  stands 
as  No.  21,185  in  the  Catalogue  of  Lalande.  It  almost 
attains  the  seventh  magnitude  (6.8).  Its  distance  is 
64  trillion  kilometers  (39  ]/?•  trillion  miles). 

The  third  of  which  the  distance  has  been  measured 
is  the  small  star  in  Cygnus,  already  referred  to  in  Chap- 
ter II,  in  describing  the  Constellations.  Its  distance  is 
69  trillion  kilometers  (42^  trillion  miles).  This,  too, 
is  a  double  star.  The  light  takes  seven  years  to 
reach  us. 

As  we  have  seen,  the  fine  stars  Sirius,  Procyon, 
Aldebaran,  Altai'r,  Vega,  and  Capella  are  more  remote. 

Our  solar  system  is  thus  very  isolated  in  the  vastness 
of  Infinitude.  The  latest  known  planet  of  our  system, 
Neptune,  performs  its  revolutions  in  space  at  4  milliards, 
470  million  kilometers  (2,771,400,000  miles)  from  our 
Sun.  Even  this  is  a  respectable  distance!  But  beyond 
this  world,  an  immense  gulf,  almost  a  void  abyss,  ex- 
tends to  the  nearest  star,  a  of  the  Centaur.  Between 
Neptune  and  Centauris  there  is  no  star  to  cheer  the 
black  and  cold  solitude  of  the  immense  vacuum.  One 
or  two  unknown  planets,  some  wandering  comets,  and 
swarms  of  meteors,  doubtless  traverse  those  unknown 
spaces,  but  all  invisible  to  us. 

Later  on  we  will  discuss  the  methods  that  have  been 

65 


ASTRONOMY   FOR   AMATEURS 

employed   in   measuring  these  distances.     Let  us  now 
continue  our  description. 


Now  that  we  have  some  notion  of  the  distance  of 
the  stars  we  must  approach  them  with  the  telescope,  and 
compare  them  one  with  another. 

Let  us,  for  example,  get  close  to  Sirius:  in  this  star 
we  admire  a  sun  that  is  several  times  heavier  than  our 
own,  and  of  much  greater  mass,  accompanied  by  a 
second  sun  that  revolves  round  it  in  fifty  years.  Its 
light  is  exceedingly  white,  and  it  notably  burns  with 
hydrogen  flames,  like  Vega  and  Altair. 

Now  let  us  approach  Arcturus,  Capella,  Aldebaran: 
these  are  yellow  stars  with  golden  rays,  like  our  Sun,  and 
the  vapor  of  iron,  of  sodium,  and  of  many  other  metals 
can  be  identified  in  their  spectrum.  These  stars  are 
older  than  the  first,  and  the  ruddy  ones,  such  as  An- 
tares,  Betelgeuse,  a  of  Hercules,  are  still  older;  several 
of  them  are  variable,  and  are  on  their  way  to  final  ex- 
tinction. 

The  Heavens  afford  us  a  perennial  store  of  treasure, 
wherein  the  thinker,  poet  or  artist  can  find  inexhaustible 
subjects  of  contemplation. 

You  have  heard  of  the  celestial  jewels,  the  diamonds, 
rubies,  emeralds,  sapphires,  topazes,  and  other  precious 

66 


THE  STARS,  SUNS  OF  THE  INFINITE 

stones  of  the  sidereal  casket.     These  marvels  are  met 
with  especially  among  the  double  stars. 

Our  Sun,  white  and  solitary,  gives  no  idea  of  the 
real  aspect  of  some  of  its  brothers  in  Infinitude.  There 
are  as  many  different  types  as  there  are  suns! 

Stars,  you  will  think,  are  like  individuals:  each  has 
its  distinct  characteristics:  no  two  are  comparable. 
And  indeed  this  reflection  is  justified.  While  human 
vanity  does  homage  to  Phoebus,  divine  King  of  the 
Heavens,  other  suns  of  still  greater  magnificence  form 
groups  of  two  or  three  splendid  orbs,  which  roll  the 
prodigious  combinations  of  their  double,  triple,  or 
multiple  systems  through  space,  pouring  on  to  the  worlds 
that  accompany  them  a  flood  of  changing  light,  now 
blue,  now  red,  now  violet,  etc. 

In  the  inexhaustible  variety  of  Creation  there  exist 
Cuns  that  are  united  in  pairs,  bound  by  a  common 
ccstiny,  cradled  in  the  same  attraction,  and  often  colored 
in  the  most  delicate  and  entrancing  shades  conceivable. 
Here  will  be  a  dazzling  ruby,  its  glowing  color  shedding 
joy;  there  a  deep  blue  sapphire  of  tender  tone;  beyond, 
the  finest  emeralds,  hue  of  hope.  Diamonds  of  translu- 
cent purity  and  whiteness  sparkle  from  the  abyss,  and 
shed  their  penetrating  light  into  the  vast  space.  What 
splendors  are  scattered  broadcast  over  the  sky!  what 
profusion ! 

6  67 


ASTRONOMY  FOR  AMATEURS 

To  the  naked  eye,  the  groups  appear  like  ordinary 
stars,  mere  luminous  points  of  greater  or  less  brilliancy; 
but  the  telescope  soon  discovers  the  beauty  of  these 
systems;  the  star  is  duplicated  into  two  distinct  suns, 
in  close  proximity.  These  groups  of  two  or  several 
suns  are  not  merely  due  to  an  effect  of  perspective — /.  e.9 
the  presence  of  two  or  more  stars  in  our  line  of  sight; 
as  a  rule  they  constitute  real  physical  systems,  and  these 
suns,  associated  in  a  common  lot,  rotate  round  one 
another  in  a  more  or  less  rapid  period,  that  varies  for 
each  system. 

One  of  the  most  splendid  of  these  double  stars,  and 
at  the  same  time  one  of  the  easiest  to  perceive,  is  £  in 
the  Great  Bear,  or  Mizar,  mentioned  above  in  de- 
scribing this  constellation.  It  has  no  contrasting  colors, 
but  exactly  resembles  twin  diamonds  of  the  finest 
water,  which  fascinate  the  gaze,  even  through  a  small 
objective. 

Its  components  are  of  the  second  and  fourth  magni- 
tudes, their  distance  =  14"*.  Some  idea  of  their  ap- 
pearance in  a  small  telescope  may  be  obtained  from  the 
subjoined  figure  (Fig.  17). 

Another  very  brilliant  pair  is  Castor.     Magnitudes 

*  14"—  14  seconds  of  arc.  One  second  of  the  circle  is  an  exceedingly  minute 
quantity.  It  is  I  millimeter  seen  at  a  distance  of  206  meters.  One  millimeter 
seen  at  a  distance  of  20  m.  6a  =  10  sees.  These  values  are  invisible  to  the 
unaided  eye. 

68 


THE  STARS,  SUNS  OF  THE  INFINITE 

second  and  third.  Distance  *5"'6.  Very  easy  to  observe. 
7  in  the  Virgin  resolves  into  two  splendid  diamonds 
of  third  magnitude.  Distance,  '5"'o.  Another  double 
star  is  7  of  the  Ram,  of  fourth  magnitude.  Distance,  *8"'9. 
And  here  are  two  that  are  even  more  curious  by 
reason  of  their  coloring:  7  in  Andromeda,  composed 


FIG.  17. — The  double  star  Mizar. 

of  a  fine  orange  star,  and  one  emerald-green,  which 
again  is  accompanied  by  a  tiny  comrade  of  the  deepest 
blue.  This  group  in  a  good  telescope  is  most  attractive. 
Magnitudes,  second  and  fifth.  Distance,  10". 

ft  of  the  Swan,  or  Albireo,   referred  to  in  the  last 
chapter,  has  been  analyzed  into  two  stars:  one  golden- 

69 


ASTRONOMY  FOR  AMATEURS 

yellow,  the  other  sapphire.  Magnitudes,  third  and 
fifth.  Distance,  34".  a  of  the  Greyhounds,  known 
also  as  the  Heart  of  Charles  II,  is  golden-yellow 
and  lilac.  Magnitudes,  third  and  fifth.  Distance 
26*;* 

a  of  Hercules  revolves  a  splendid  emerald  and  a 
ruby  in  the  skies;  f  of  the  Lyre  exhibits  a  yellow  and  a 
green  star;  Rigel,  an  electric  sun,  and  a  small  sapphire; 
Antares  is  ruddy  and  emerald-green;  77  of  Perseus  re- 
solves into  a  burning  red  star,  and  one  smaller  that  is 
deep  blue,  and  so  on. 

These  exquisite  double  stars  revolve  in  gracious  and 
splendid  couples  around  one  another,  as  in  some  majestic 
valse,  marrying  their  multicolored  fires  in  the  midst 
of  the  starry  firmament. 

Here,  we  constantly  receive  a  pure  and  dazzling 
white  light  from  our  burning  luminary.  Its  ray,  indeed, 
contains  the  potentiality  of  every  conceivable  color, 
but  picture  the  fantastic  illumination  of  the  worlds  that 
gravitate  round  these  multiple  and  colored  suns  as 
they  shed  floods  of  blue  and  roseate,  red,  or  orange 
light  around  them!  What  a  fairy  spectacle  must  life 
present  upon  these  distant  universes! 

*  These  fine  double  stars  can  be  observed  with  the  help  of  the  smallest  tele- 
scope. 

70 


THE  STARS,  SUNS  OF  THE  INFINITE 

Let  us  suppose  that  we  inhabit  a  planet  illuminated 
by  two  suns,  one  blue,  the  other  red. 

It  is  morning.  The  sapphire  sun  climbs  slowly 
up  the  Heavens,  coloring  the  atmosphere  with  a  somber 
and  almost  melancholy  hue.  The  blue  disk  attains 
the  zenith,  and  is  beginning  its  descent  toward  the 
West,  when  the  East  lights  up  with  the  flames  of  a  scar- 
let sun,  which  in  its  turn  ascends  the  heights  of  the 
firmament.  The  West  is  plunged  in  the  penumbra 
of  the  rays  of  the  bjue  sun,  while  the  East  is  illuminated 
with  the  purple  and  burning  rays  of  the  ruby  orb. 

The  first  sun  is  setting  when  the  second  noon  shines 
for  the  inhabitants  of  this  strange  world.  But  the  red 
sun,  too,  accomplishes  the  law  of  its  destiny.  Hardly 
has  it  disappeared  in  the  conflagration  of  its  last  rays, 
with  which  the  West  is  flushed,  when  the  blue  orb 
reappears  on  the  opposite  side,  shedding  a  pale  azure 
light  upon  the  world  it  illuminates,  which  knows  no 
night.  And  thus  these  two  suns  fraternize  in  the 
Heavens  over  the  common  task  of  renewing  a  thousand 
effects  of  extra-terrestrial  light  for  the  globes  that  are 
subject  to  their  variations. 

Scarlet,  indigo,  green,  and  golden  suns;  pearly  and 
multicolored  Moons;  are  these  not  fairy  visions,  dazzling 
to  our  poor  sight,  condemned  while  here  below  to  see 
and  know  but  one  white  Sun  ? 

71 


ASTRONOMY  FOR  AMATEURS 

As  we  have  learned,  there  are  not  only  double,  but 
triple,  and  also  multiple  stars.  One  of  the  finest  ter- 
nary systems  is  that  of  7  in  Andromeda,  above  mentioned. 
Its  large  star  is  orange,  its  second  green,  its  third  blue, 
but  the  two  last  are  in  close  juxtaposition,  and  a  powerful 
telescope  is  needed  to  separate  them.  A  triple  star  more 


FIG.  1 8. — Triple  star  I  in  Cancer. 

easy  to  observe  is  £  of  Cancer,  composed  of  three  orbs 
of  fifth  magnitude,  at  a  distance  of  i"  and  5*;  the  first 
two  revolve  round  their  common  center  of  gravity  in 
fifty-nine  years,  the  third  takes  over  three  hundred 
years.  The  preceding  figure  shows  this  system  in  a 
fairly  powerful  objective  (Fig.  18). 

72 


THE  STARS,  SUNS  OF  THE  INFINITE 

In  the  Lyre,  a  little  above  the  dazzling  Vega,  €  is 
of  fourth  magnitude,  which  seems  a  little  elongated 
to  the  unaided  eye,  and  can  even  be  analyzed  into  two 
contiguous  stars  by  very  sharp  sight.  But  on  examining 
this  attractive  pair  with  a  small  glass,  it  is  further 
obvious  that  each  of  these  stars  is  double;  so  that  they 


FIG.  19. — Quadruple  star  6  of  the  Lyre. 

form  a  splendid  quadruple  system  of  two  couples  (Fig. 
19):  one  of  fifth  and  a  half  and  sixth  magnitudes,  at  a 
distance  of  *2"'4,  the  other  of  sixth  and  seventh,  *3"'2 
distant.  The  distance  between  the  two  pairs  is  207". 
In  speaking  of  Orion,  we  referred  to  the  marvelous 
star  0,  situated  in  the  no  less  famous  Nebula,  below 

73 


ASTRONOMY  FOR  AMATEURS 

the  Belt;  this  star  forms  a  dazzling  sextuple  system,  in 
the  very  heart  of  the  nebula  (Fig.  20).  How  different 
to  our  Sun,  sailing  through  Space  in  modest  isola- 
tion ! 

Be   it   noted   that    all   these   stars  are   animated  by 
prodigious  motions  that  impel  them  in  every  direction. 


FIG.  20. — Sextuple  star  6  in  the  Nebula  of  Orion. 

There  are  no  fixed  stars.  On  every  side  throughout 
Infinity,  the  burning  suns — enormous  globes,  blazing 
centers  of  light  and  heat — are  flying  at  giddy  speed 
toward  an  unknown  goal,  traversing  millions  of  miles 
each  day,  crossing  century  by  century  such  vast  spaces 
as  are  inconceivable  to  the  human  intellect. 

74 


THE  STARS,  SUNS  OF  THE  INFINITE 

If  the  stars  appear  motionless  to  us,  it  is  because 
they  are  so  remote,  their  secular  movements  being  only 
manifested  on  the  celestial  sphere  by  imperceptible 
displacements.  But  in  reality  these  suns  are  in  per- 
petual commotion  in  the  abysses  of  the  Heavens,  which 
they  quicken  with  an  extraordinary  animation. 

These  perpetual  and  cumulative  motions  must 
eventually  modify  the  aspect  of  the  Constellations: 
but  these  changes  will  only  take  effect  very  slowly;  and 
for  thousands  and  thousands  of  years  longer  the  heroes 
and  heroines  of  mythology  will  keep  their  respective 
places  in  the  Heavens,  and  reign  undisturbed  beneath 
the  starry  vault. 

Examination  of  these  star  motions  reveals  the  fact 
that  our  Sun  is  plunging  with  all  his  system  (the  Earth 
included)  toward  the  Constellation  of  Hercules.  We 
are  changing  our  position  every  moment:  in  an  hour 
we  shall  be  70,000  kilometers  (43,500  miles)  farther 
than  we  are  at  present.  The  Sun  and  the  Earth  will 
never  again  traverse  the  space  they  have  just  left,  and 
which  they  have  deserted  forever. 

And  here  let  us  pause  for  an  instant  to  consider  the 
variable  stars.  Our  Sun,  which  is  constant  and  uniform 
in  its  light,  does  not  set  the  type 'of  all  the  stars.  A 
great  number  of  them  are  variable — either  periodically, 
in  regular  cycles — or  irregularly. 

75 


ASTRONOMY  FOR  AMATEURS 

We  are  already  acquainted  with  the  variations  of 
Algol,  in  Perseus,  due  to  its  partial  eclipse  by  a  dark 
globe  gravitating  in  the  line  of  our  vision.  There  are 
several  others  of  the  same  type:  these  are  not,  properly 
speaking,  variable  stars.  But  there  are  many  others 
the  intrinsic  light  of  which  undergoes  actual  variations. 

In  order  to  realize  this,  let  us  imagine  that  our  Earth 
belongs  to  such  a  sun,  for  example,  to  a  star  in  the 
southern  constellation  of  the  Whale,  indicated  by  the 
letter  o,  which  has  been  named  the  "wonderful"  (Mira 
Ceti).  Our  new  sun  is  shining  to-day  with  a  dazzling 
light,  shedding  the  gladness  of  his  joyous  beams  upon 
nature  and  in  our  hearts.  For  two  months  we  admire 
the  superb  orb,  sparkling  in  the  azure  illuminated 
with  its  radiance.  Then  of  a  sudden,  its  light  fades, 
and  diminishes  in  intensity,  though  the  sky  remains 
clear.  Imperceptibly,  our  fine  sun  darkens;  the  at- 
mosphere becomes  sad  and  dull,  there  is  an  anticipation 
of  universal  death.  For  five  long  months  our  world 
is  plunged  in  a  kind  of  penumbra;  all  nature  is  saddened 
in  the  general  woe. 

But  while  we  are  bewailing  the  cruelty  of  our  lot, 
our  cherished  luminary  revives.  The  intensity  of  its 
light  increases  slowly.  Its  brilliancy  augments,  and 
finally,  at  the  end  of  three  months,  it  has  recovered  its 
former  splendors,  and  showers  its  bright  beams  upon  our 

76 


THE  STARS,  SUNS  OF  THE  INFINITE 

world,  flooding  it  with  joy.  But — we  must  not  rejoice 
too  quickly!  This  splendid  blaze  will  not  endure.  The 
flaming  star  will  pale  once  more;  fade  back  to  its  mini- 
mum; and  then  again  revive.  Such  is  the  nature  of  this 
capricious  sun.  It  varies  in  three  hundred  and  thirty- 
one  days,  and  from  yellow  at  the  maximum,  turns  red 
at  the  minimum.  This  star,  Mira  Ceti,  which  is  one 
of  the  most  curious  of  its  type,  varies  from  the  second 
to  the  ninth  magnitudes:  we  cite  it  as  one  example; 
hundreds  of  others  might  be  instanced. 

Thus  the  sky  is  no  black  curtain  dotted  with  brilliant 
points,  no  empty  desert,  silent  and  monotonous.  It 
is  a  prodigious  theater  on  which  the  most  fantastic  plays 
are  continually  being  acted.  Only — there  are  no 
spectators. 

Again,  we  must  note  the  temporary  stars,  which  shine 
for  a  certain  time,  and  then  die  out  rapidly.  Such 
was  the  star  in  Cassiopeia,  in  1572,  the  light  of  which 
exceeded  Sirius  in  its  visibility  in  full  daylight,  burn- 
ing for  five  months  with  unparalleled  splendor,  domi- 
nating all  other  stars  of  first  magnitude;  after  which  it 
died  out  gradually,  disappearing  at  the  end  of  seventeen 
months,  to  the  terror  of  the  peoples,  who  saw  in  it  the 
harbinger  of  the  world's  end:  that  of  1604,  in  the  Con- 
stellation of  the  Serpent,  which  shone  for  a  year;  of 
1866,  of  second  magnitude,  in  the  Northern  Crown, 

77 


ASTRONOMY  FOR  AMATEURS 

which  appeared  for  a  few  weeks  only;  of  1876,  in  the 
Swan;  of  1885,  in  the  Nebula  of  Andromeda;  of  1891, 
in  the  Charioteer;  and  quite  recently,  of  1901,  in  Perseus. 
These  temporary  stars,  which  appear  spontaneously 
to  the  observers  on  the  Earth,  and  quickly  vanish  again, 
are  doubtless  due  to  collisions,  conflagrations,  or  celestial 
cataclysms.  But  we  only  see  them  long  after  the  epoch 
at  which  the  phenomena  occurred,  years  upon  years,  and 
centuries  ago.  For  instance,  the  conflagration  photo- 
graphed by  the  author  in  1901,  in  Perseus,  must  have 
occurred  in  the  time  of  Queen  Elizabeth.  It  has  taken 
all  this  time  for  the  rays  of  light  to  reach  us. 

The  Heavens  are  full  of  surprises,  on  which  we  can 
bestow  but  a  fleeting  glance  within  these  limits.  They 
present  a  field  of  infinite  variety. 

Who  has  not  noticed  the  Milky  Way,  the  pale  belt 
that  traverses  the  entire  firmament  and  is  so  luminous 
on  clear  evenings  in  the  Constellations  of  the  Swan  and 
the  Lyre  ?  It  is  indeed  a  swarm  of  stars.  Each  is  in- 
dividually too  small  to  excite  our  retina,  but  as  a  whole, 
curiously  enough,  they  are  perfectly  visible.  With 
opera-glasses  we  divine  the  starry  constitution:  a  small 
telescope  shows  us  marvels.  Eighteen  millions  of  stars 
were  counted  there  with  the  gauges  of  William  Herschel. 

Now  this  Milky  Way  is  a  symbol,  not  of  the  Universe, 

78 


THE  STARS,  SUNS  OF  THE  INFINITE 

but  of  the  Universes  that  succeed  each   other  through 
the  vast  spaces  to  Infinity. 

Our  Sun  is  a  star  of  the  Milky  Way.  It  surrounds 
us  like  a  great  circle,  and  if  the  Earth  were  transparent, 
we  should  see  it  pass  beneath  our  feet  as  well  as  over 
our  heads.  It  consists  of  a  very  considerable  mass  of 


FIG.  21. — The  Star-Cluster  in  Hercules. 

star-(  lusters,  varying  greatly  in  extent  and  number, 
some  projected  in  front  of  others,  while  the  whole  forms 
an  agglomeration. 

Among  this  mass  of  star-groups,  several  thousands 
of  which  are  already  known  to  us,  we  will  select  one  of 
the  most  curious,  the  Cluster  in  Hercules,  which  can  be 

79 


ASTRONOMY  FOR  AMATEURS 

distinguished  with  the  unaided  eye,  between  the  stars 
rj  and  f  of  that  constellation.  Many  photographs  of 
it  have  been  taken  in  the  author's  observatory  at  Juvisy, 
showing  some  thousands  of  stars;  and  one  of  these  is 
reproduced  in  the  accompanying  figure  (Fig.  21).  Is 
it  not  a  veritable  universe  ? 


FIG.  22. — The  Star-Cluster  in  the  Centaur. 

Another  of  the  most  beautiful,  on  account  of  its 
regularity,  is  that  of  the  Centaur  (Fig.  22). 

These  groups  often  assume  the  most  extraordinary 
shapes  in  the  telescope,  such  as  crowns,  fishes,  crabs, 
open  mouths,  birds  with  outspread  wings,  etc. 

We  must  also  note  the  gaseous  nebula,  universes  in 
80 


THE  STARS,  SUNS  OF  THE  INFINITE 

the    making,    e.  £.,   the    famous    Nebula    in    Orion,    of 
which  we  obtained  some  notion  a  while  ago  in  conneo 


FIG.  23. — The  Nebula  in  Andromeda. 

tion  with  its  sextuple  star:  and  also  that  in  Andromeda 
(Fig.  23). 

81 


ASTRONOMY  FOR   AMATEURS 

Perhaps  the  most  marvelous  of  all   is   that  of  the 
Greyhounds,  which  evolves  in  gigantic  spirals  round  a 


FIG.  24. — Nebula  in  the  Greyhounds. 

dazzling  focus,  and  then  loses   itself  far  off  in  the  re 
cesses  of  space.     Fig.  24  gives  a  picture  of  it. 

82 


THE  STARS,  SUNS  OF  THE  INFINITE 

Without  going  thus  far,  and  penetrating  into  telescop- 
ic depths,  my  readers  can  get  some  notion  of  these  star- 
clusters  with  the  help  of  a  small  telescope  or  opera- 
glasses,  or  even  with  the  unaided  eye,  by  looking  at  the 
beautiful  group  of  the  Pleiades,  already  familiar  to  us 
on  another  page,  and  using  it  as  a  test  of  vision.  The 
little  map  subjoined  (Fig.  25)  will  be  an  assistance  in 

Asterope  I 

^fi  Taygete 

Asterope  II  '^ 

\^ 

Maya 

A  \ 

/  \  1 

\       i 
X 

Pleione  X*  \  I 

*  ^-' 


Atla, 


FIG.  25.—  The  Pleiades. 


recognizing  them,  and  in  estimating  their  magnitudes, 
which  are  in  the  following  order: 

Alcyone  ...............  .    ..........  3.0. 

Electra  ............................  4.5. 

Atlas  .............................  4.6. 

Maia  .............................  5.0. 

Merope  ..........................  5.5. 

Taygeta  ..........................  5.8. 

7  83 


ASTRONOMY  FOR  AMATEURS 

Pleione 6.3, 

Celaeno 6.5. 

Asterope 6.8. 

Good  eyes  distinguish  the  first  six,  sharp  sight  de- 
tects the  three  others. 

In  the  times  of  the  ancient  Greeks,  seven  were  ac- 
counted of  equal  brilliancy,  and  the  poets  related  that 
the  seventh  star  had  fled  at  the  time  of  the  Trojan  War. 
Ovid  adds  that  she  was  mortified  at  not  being  embraced 
by  a  god,  as  were  her  six  sisters.  It  is  probable  that  only 
the  best  sight  could  then  distinguish  Heione,  as  in  our 
own  day.  The  angular  distance  from  Atlas  to  Pleione 
is  5'. 

The  length  of  this  republic,  from  Atlas  and  Pleione 
to  Celaeno,  is  \' /^^'  of  time,  or  i°  6'  of  arc;  the  breadth, 
from  Merope  to  Asterope,  is  36'.* 

In  the  quadrilateral,  the  length  from  Alcyone  to 
Electra  is  36',  and  the  breadth  from  Merope  to  Maia 
25'.  To  us  it  appears  as  though,  if  the  Full  Moon  were 
placed  in  front  of  this  group  of  nine  stars,  she  would 
cover  it  entirely,  for  to  the  naked  eye  she  appears  much 
larger  than  all  the  Pleiades  together.  But  this  is  not  so. 
She  only  measures  31',  less  than  half  the  distance  from 
Atlas  to  Celaeno;  she  is  hardly  broader  than  the  distance 

*  For  the  explanation  of  the  angular  distances  of  degrees,  minutes,  and  sec 
onds,  see  Chapter  XI,  on  Methods  of  Measurement. 

84 


THE  STARS,  SUNS  OF  THE  INFINITE 

from  Alcyone  to  Atlas,  and  could  pass  between  Merope 
and  Taygeta  without  touching  either  of  these  stars. 
This  is  a  perennial  and  very  curious  optical  illusion. 
When  the  Moon  passes  in  front  of  the  Pleiades,  and 
occults  them  successively,  it  is  hard  to  believe  one's 


FIG.  26. — Occultation  of  the  Pleiades  by  the  Moon. 

eyes.  The  fact  occurred,  e.  g.,  on  July  23,  1897,  during 
a  fine  occultation  observed  at  the  author's  laboratory 
of  Juvisy  (Fig.  26). 

Photography  here  discovers  to  us,  not  6,  9,  12,  15, 
or  20  stars,  but  hundreds  and  millions. 

85 


ASTRONOMY  FOR  AMATEURS 

These  are  the  most  brilliant  flowers  of  the  celestial 
garden. 

We,  alas,  can  but  glance  at  them  rapidly.  In  con- 
templating them  we  are  transported  into  immensities 
both  of  space  and  time,  for  the  stellar  periods  measured 
by  these  distant  universes  often  overpower  in  their  mag- 
nitude the  rapid  years  in  which  our  terrestrial  days  are 


FIG.  27. — Stellar  dial  of  the  double  star  7  of  the  Virgin. 

estimated.  For  instance,  one  of  the  double  stars  we 
spoke  of  above,  7  of  the  Virgin,  sees  its  two  components, 
translucent  diamonds,  revolve  around  their  common 
center  of  gravity,  in  one  hundred  and  eighty  years. 
How  many  events  took  place  in  France,  let  us  say,  in  a 
single  year  of  this  star! — The  Regency,  Louis  XV,  Louis 
XVI,  the  Revolution,  Napoleon,  Louis  XVIII,  Louis 

86 


THE  STARS,  SUNS  OF  THE  INFINITE 

Philippe,  the  Second  Republic,  Napoleon  III,  the 
Franco-German  War,  the  Third  Republic.  .  .  .  What 
revolutions  here,  during  a  single  year  of  this  radiant 
pair!  (Fig.  27.) 

But  the  pageant  of  the  Heavens  is  too  vast,  too  over- 
whelming. We  must  end  our  survey. 

Our  Milky  Way,  with  its  millions  of  stars,  represents 
for  us  only  a  portion  of  the  Creation.  The  illimitable 
abysses  of  Infinitude  are  peopled  by  other  universes  as 
vast,  as  imposing,  as  our  own,  which  are  renewed  in  all 
directions  through  the  depths  of  Space  to  endless  dis- 
tance. Where  is  our  little  Earth  ?  Where  our  Solar 
System  ?  We  are  fain  to  fold  our  wings,  and  return  from 
the  Immense  and  Infinite  to  our  floating  island. 


CHAPTER  IV 

OUR   STAR   THE   SUN 

IN  the  incessant  agitation  of  daily  life  in  which  we 
are  involved  by  the  thousand  superfluous  wants  of 
modern  "civilization,"  one  is  prone  to  assume  that  ex- 
istence is  complete  only  when  it  reckons  to  the  good  an 
incalculable  number  of  petty  incidents,  each  more  in- 
significant than  the  last.  Why  lose  time  in  thinking 
or  dreaming  ?  We  must  live  at  fever  heat,  must  agitate, 
and  be  infatuated  for  inanities,  must  create  imaginary 
desires  and  torments. 

The  thoughtful  mind,  prone  to  contemplation  and 
admiration  of  the  beauties  of  Nature,  is  ill  at  ease  in  this 
perpetual  vortex  that  swallows  everything — satisfaction, 
in  a  life  that  one  has  not  time  to  relish;  love  of  the 
beautiful,  that  one  views  with  indifference;  it  is  a  whirl- 
pool that  perpetually  hides  Truth  from  us,  forgotten 
forever  at  the  bottom  of  her  well. 

And  why  are  our  lives  thus  absorbed  in  merely 
material  interests?  To  satisfy  our  pride  and  vanity! 
To  make  ourselves  slaves  to  chimeras!  If  the  Moon 

88 


OUR  STAR  THE  SUN 

were  inhabited,  and  if  her  denizens  could  see  us  plainly 
enough  to  note  and  analyze  the  details  of  human  exist- 
ence on  the  surface  of  our  planet,  it  would  be  curious 
and  perhaps  a  little  humiliating  for  us,  to  see  their 
statistics.  What!  we  should  say,  is  this  the  sum  of  our 
lives  ?  Is  it  for  this  that  we  struggle,  and  suffer,  and 
die  ?  Truly  it  is  futile  to  give  ourselves  such  trouble. 

And  yet  the  remedy  is  simple,  within  the  power  of 
every  one;  but  one  does  not  think  of  it  just  because  it 
is  too  easy,  although  it  has  the  immense  advantage  of 
lifting  us  out  of  the  miseries  of  this  weary  world  toward 
the  inexpressible  happiness  that  must  always  awaken 
in  us  with  the  knowledge  of  the  Truth:  we  need  only 
open  our  eyes  to  see,  and  to  look  out.  Only — one 
hardly  ever  thinks  of  it,  and  it  is  easier  to  let  one's  self 
be  blinded  by  the  illusion  and  false  glamor  of  appear- 
ances. 

Think  what  it  would  be  to  consecrate  an  hour  each 
day  to  voluntary  participation  in  the  harmonious  Choir 
of  Nature,  to  raise  one's  eyes  toward  the  Heavens, 
to  share  the  lessons  taught  by  the  Pageant  of  the  Uni- 
verse! But,  no:  there  is  no  time,  no  time  for  the 
intellectual  life,  no  time  to  become  attached  to  real 
interests,  no  time  to  pursue  them. 

Among  the  objects  marshaled  for  us  in  the  immenst 
spectacle  of  Nature,  nothing  without  exception  has 

89 


ASTRONOMY  FOR  AMATEURS 

Struck  the  admiration  and  attention  of  man  as  much 
as  the  Sun,  the  God  of  Light,  the  fecundating  orb, 
without  which  our  planet  and  its  life  would  never  have 
issued  from  nonentity,  the  visible  image  of  the  invisible 
gody  as  said  Cicero,  and  the  poets  of  antiquity.  And 
yet  how  many  beyond  the  circle  of  those  likely  to  read 
these  pages  know  that  this  Sun  is  a  star  in  the  Milky 
Way,  and  that  every  star  is  a  sun  ?  How  many  take 
any  account  of  the  reality  and  grandeur  of  the  Uni- 
verse ?  Inquire,  and  you  will  find  that  the  number  of 
people  who  have  any  notion,  however  rudimentary,  of 
its  construction,  is  singularly  restricted.  Humanity  is 
content  to  vegetate,  much  after  the  fashion  of  a  race  of 
moles. 

Henceforward,  you  will  know  that  you  are  living 
in  the  rays  of  a  star,  which,  from  its  proximity,  we  term 
a  sun.  To  the  inhabitants  of  other  systems  of  worlds,  our 
splendid  Sun  is  only  a  more  or  less  brilliant,  luminous 
point,  according  as  the  spot  from  which  it  is  observed 
is  nearer  or  farther  off.  But  to  us  its  "terrestrial" 
importance  renders  it  particularly  precious  ;  we  forget 
all  the  sister  stars  on  its  account,  and  even  the  most 
ignorant  hail  it  with  enthusiasm  without  exactly  knowing 
what  its  role  in  the  universe  may  be,  simply  because  they 
feel  that  they  depend  on  it,  and  that  without  it  life 
would  become  extinct  on  this  globe.  Yes,  it  is  the 

90 


OUR  STAR  THE  SUN 

beneficent  rays  of  the  Sun  that  shed  upon  our  Earth  the 
floods  of  light  and  heat  to  which  Life  owes  its  existence 
and  its  perpetual  propagation. 

Hail,  vast  Sun!  a  little  star  in  Infinitude,  but  for  us 
a  colossal  and  portentous  luminary.  Hail,  divine  Bene- 
factor! How  should  we  not  adore,  when  we  owe  him 
the  glow  of  the  warm  and  cheery  days  of  summer,  the 
gentle  caresses  by  which  his  rays  touch  the  undulating 
ears,  and  gild  them  with  the  touch  ?  The  Sun  sustains 
our  globe  in  Space,  and  keeps  it  within  his  rays  by  the 
mysteriously  powerful  and  delicate  cords  of  attraction. 
It  is  the  Sun  that  we  inhale  from  the  embalmed  corollas 
of  the  flowers  that  uplift  their  gracious  heads  toward 
his  light,  and  reflect  his  splendors  back  to  us.  It  is  the 
Sun  that  sparkles  in  the  foam  of  the  merry  wine;  that 
charms  our  gaze  in  those  first  days  of  spring,  when 
the  home  of  the  human  race  is  adorned  with  all  the 
charms  of  verdant  and  flowering  youth.  Everywhere 
we  find  the  Sun;  everywhere  we  recognize  his  work, 
extending  from  the  infinitely  great  to  the  infinitely 
little.  We  bow  to  his  might,  and  admire  his  power. 
When  in  the  sad  winter  day  he  disappears  behind  the 
snowy  eaves,  we  think  his  fiery  globe  will  never  rise  to 
mitigate  the  short  December  days  which  are  alleviated 
with  his  languid  beams. 

April  restores  him  to  superb  majesty,  and  our  hearts 

91 


ASTRONOMY  FOR  AMATEURS 

are  filled  with  hope  in  the  illumination  of  those  beau- 
teous, sunny  hours. 


Our  celestial  journey  carried  us  far  indeed  from 
our  own  Solar  System.  Guided  by  the  penetrating  eye 
of  the  telescope,  we  reached  such  distant  creations 
that  we  lost  sight  of  our  cherished  luminary. 

But  we  remember  that  he  burns  yonder,  in  the  midst 
of  the  pale  cosmic  cloud  we  term  the  Milky  Way.  Let 
us  approach  him,  now  that  we  have  \icited  the  Isles 
of  Light  in  the  Celestial  Ocean;  let  us  traverse  the  vast 
plains  strewn  with  the  burning  gold  of  the  Suns  of  the 
Infinite. 

We  embark  upon  a  ray  of  light,  and  glide  rapidly 
to  the  portals  of  our  Universe.  Soon  we  perceive  a 
tiny  speck,  scintillating  feebly  in  the  depths  of  Space, 
and  recognize  it  as  our  own  celestial  quarters.  This 
little  star  shines  like  the  head  of  a  gold  pin,  and  in- 
creases in  size  as  we  advance  toward  it.  We  traverse 
a  few  more  trillion  miles  in  our  rapid  course,  and  it 
shines  out  like  a  fine  star  of  the  first  magnitude.  It 
grows  larger  and  larger.  Soon  we  divine  that  it  is 
our  humble  Earth  that  is  shining  before  us,  and  gladly 
alight  upon  her.  In  future  we  shall  not  quit  our  own 
province  of  the  Celestial  Kingdom,  but  will  enter  into 

92 


OUR  STAR  THE  SUN 

relations  with  this  solar  family,  which  interests  us  the 
more  in  that  it  affects  us  so  closely. 


FIG.  28. — Comparative  sizes  of  the  Sun  and  Earth. 

The  Sun,  which  is  manifested  to  us  as  a  fine  white 
disk  at  noon,  while  it  is  fiery  red  in  the  evening,  at  its 
setting,  is  an  immense  globe,  whose  colossal  dimensions 

93 


ASTRONOMY  FOR  AMATEURS 

surpass  those  of  our  terrestrial  atom  beyond  all  con- 
ceivable proportion. 

In  diameter,  it  is,  in  effect,  108^  times  as  large  as 
the  Earth;  that  is  to  say,  if  our  planet  be  represented  by 
a  globe  i  meter  in  diameter,  the  Sun  would  figure  as  a 
sphere  108^  meters  across.  This  is  shown  on  the  ac- 
companying figure  (Fig.  28),  which  is  in  exact  propor- 
tion. 

If  our  world  were  set  down  upon  the  Sun,  with  all  its 
magnificence,  all  its  wealth,  its  mountains,  its  seas,  its 
monuments,  and  its  inhabitants,  it  would  only  be  an  im- 
perceptible speck.  It  would  occupy  less  space  in  the 
central  orb  than  one  grain  in  a  grenade.  If  the  Earth 
were  placed  in  the  center  of  the  Sun,  with  the  Moon 
still  revolving  round  it  at  her  proper  distance  of  384,- 
ooo  kilometers  (238,500  miles),  only  half  the  solar  sur- 
face would  be  covered. 

In  volume  the  Sun  is  1,280,000  times  vaster  than 
our  abode,  and  324,000  times  heavier  in  mass.  That 
the  giant  only  appears  to  us  as  a  small  though  very 
brilliant  disk,  is  solely  on  account  of  its  distance.  Its 
apparent  dimensions  by  no  means  reveal  its  majestic 
proportions  to  us. 

When  observed  with  astronomical  instruments,  or 
photographed,  we  discover  that  its  surface  is  not  smooth, 
as  might  be  supposed,  but  granulated,  presenting  a 

94 


OUR  STAR  THE  SUN 

number  of  luminous  points  dispersed  over  a  more 
somber  background.  These  granulations  are  somewhat 
like  the  pores  of  a  fruit,  e.  g.y  a  fine  orange,  the  color  of 
which  recalls  the  hue  of  the  Sun  when  it  sinks  in  the 
evening,  and  prepares  to  plunge  us  into  darkness.  At 
times  these  pores  open  under  the  influence  of  disturb- 
ances that  arise  upon  the  solar  surface,  and  give  birth 
to  a  Sun-Spot.  For  centuries  scientists  and  lay  people 
alike  refused  to  admit  the  existence  of  these  spots,  re- 
garding them  as  so  many  blemishes  upon  the  King  of 
the  Heavens.  Was  not  the  Sun  the  emblem  of  inviolable 
purity  ?  To  find  any  defect  in  him  were  to  do  him 
grievous  injury.  Since  the  orb  of  day  was  incorruptible, 
those  who  threw  doubt  on  his  immaculate  splendor  were 
fools  and  idiots.  And  so  when  Scheiner,  one  of  the 
first  who  studied  the  solar  spots  with  the  telescope, 
published  the  result  of  his  experiments  in  1610,  no  one 
would  believe  his  statements. 

Yet,  from  the  observations  of  Galileo  and  other 
astronomers,  it  became  necessary  to  accept  the  evidence, 
and  stranger  still  to  recognize  that  it  is  by  these  very 
spots  that  we  are  enabled  to  study  the  physical  consti- 
tution of  the  Sun. 

They  are  generally  rounded  or  oval  in  shape,  and 
exhibit  two  distinct  parts;  first,  the  central  portion,  which 
is  black,  and  is  called  the  nucleus,  or  umbra;  second, 

95 


ASTRONOMY  FOR  AMATEURS 

a  clearer  region,  half  shaded,  which  has  received  the 
name  of  penumbra.  These  parts  are  sharply  defined 
in  outline;  the  penumbra  is  gray,  the  nucleus  looks 
black  in  relation  to  the  dazzling  brilliancy  of  the  solar 


FIG.  29. — Direct  photograph  of  the  Sun. 

surface;  but  as  a  matter  of  fact  it  radiates  a  light  2,000 
times  superior  in  intensity  to  that  of  the  full  moon. 

Some  idea  of  the  aspect  of  these  spots  may  be  ob- 
tained from  the  accompanying  reproduction  of  a  photo- 
graph of  the  Sun  (taken  September  8,  1898,  at  the 

96 


OUR  STAR  THE  SUN 

author's  observatory  at  Juvisy),  and  from  the  detailed 
drawing  of  the  large  spot  that  broke  out  same  days 
later  (September  13),  crossed  by  a  bridge,  and  furrowed 


FIG.  30. — Telescopic  aspect  of  a  Sun-Spot. 

with  flames.     As   a  rule,  the  spots  undergo  rapid  trans- 
formations. 

These  spots,  which  appear  of  insignificant  dimen- 

97 


ASTRONOMY  FOR  AMATEURS 

sions  to  the  observers  on  the  Earth,  are  in  reality  ab- 
solutely gigantic.  Some  that  have  been  measured 
are  ten  times  as  large  as  the  Earth's  diameter,  /.  e.y 
120,000  kilometers  (74,500  miles). 

Sometimes  the  spots  are  so  large  that  they  can  be  seen 
with  the  unaided  eye  (protected  with  black  or  dark-blue 
glasses).  They  are  not  formed  instantaneously,  but 
are  heralded  by  a  vast  commotion  on  the  solar  surface, 
exhibiting,  as  it  were,  luminous  waves  or  jacula.  Out 
of  this  agitation  arises  a  little  spot,  that  is  usually  round, 
and  enlarges  progressively  to  reach  a  maximum,  after 
which  it  diminishes,  with  frequent  segmentation  and 
shrinkage.  Some  are  visible  only  for  a  few  days; 
others  last  for  months.  Some  appear,  only  to  be  in- 
stantly swallowed  in  the  boiling  turmoil  of  the  flaming 
orb.  Sometimes,  again,  white  incandescent  waves 
emerge,  and  seem  to  throw  luminous  bridges  across 
the  central  umbra.  As  a  rule  the  spots  are  not  very 
profound.  They  are  funnel-shaped  depressions,  in- 
ferior in  depth  to  the  diameter  of  the  Earth,  which,  as 
we  have  seen,  is  108  times  smaller  than  that  of  the  Sun, 

The  Sun-Spots  are  not  devoid  of  motion,  and  from 
their  movements  we  learn  that  the  radiant  orb  revolves 
upon  itself  in  about  twenty-five  days.  This  rotation 
was  determined  in  1611,  by  Galileo,  who,  while  ob- 

98 


OUR  STAR  THE  SUN 

serving  the  spots,  saw  that  they  traversed  the  solar  disk 
from  east  to  west,  following  lines  that  are  oblique  to 
the  plane  of  the  ecliptic,  and  that  they  disappear  at  the 
western  border  fourteen  days  after  their  arrival  at  the 
eastern  edge.  Sometimes  the  same  spot,  after  being 
invisible  for  fourteen  days,  reappears  upon  the  eastern 
edge,  where  it  was  observed  twenty-eight  days  pre- 
viously. It  progresses  toward  the  center  of  the  Sun, 
which  is  reached  in  seven  days,  disappears  anew  in 
the  west,  and  continues  its  journey  on  the  hemisphere 
opposed  to  us,  to  reappear  under  observation  two  weeks 
later,  if  it  has  not  meantime  been  extinguished.  This 
observation  proves  that  the  Sun  revolves  upon  itself. 
The  reappearance  of  the  spots  occurs  in  about  twenty- 
seven  days,  because  the  Earth  is  not  stationary,  and 
in  its  movement  round  the  burning  focus,  a  motion 
effected  in  the  same  direction  as  the  solar  rotation, 
the  spots  are  still  visible  two  and  a  half  days  after  they 
disappeared  from  the  point  at  which  they  had  been 
twenty-five  days  previously.  In  reality,  the  rotation  of 
the  Sun  occupies  twenty-five  and  a  half  days,  but 
strangely  enough  this  globe  does  not  rotate  in  one 
uniform  period,  like  the  Earth;  the  rotation  periods,  or 
movements  of  the  different  parts  of  the  solar  surface, 
diminish  from  the  Sun's  equator  toward  its  poles.  The 
period  is  twenty-five  days  at  the  equator,  twenty-six  at 
8  99 


ASTRONOMY  FOR  AMATEURS 

the  twenty-fourth  degree  of  latitude,  north  or  south, 
twenty-seven  at  the  thirty-seventh  degree,  twenty-eight 
at  the  forty-eighth.  The  spots  are  usually  formed 
between  the  equator  and  this  latitude,  more  especially 
between  the  tenth  and  thirtieth  degrees.  They  have 
never  been  seen  round  the  poles. 

Toward  the  edges  of  the  Sun,  again,  are  very  bril- 
liant and  highly  luminous  regions,  which  generally  sur- 
round the  spots,  and  have  been  termed  faculce  (facula, 
a  little  torch).  These  faculae,  which  frequently  occupy 
a  very  extensive  surface,  seem  to  be  the  seat  of  formi- 
dable commotions  that  incessantly  revolutionize  the  face 
of  our  monarch,  often,  as  we  said,  preceding  the  spots. 
They  can  be  detected  right  up  to  the  poles. 

Our  Sun,  that  appears  so  calm  and  majestic,  is 
in  reality  the  seat  of  fierce  conflagrations.  Volcanic 
eruptions,  the  most  appalling  storms,  the  worst  cata- 
clysms that  sometimes  disturb  our  little  world,  are 
gentle  zephyrs  compared  with  the  solar  tempests  that 
engender  clouds  of  fire  capable  at  one  burst  of  engulfing 
globes  of  the  dimensions  of  our  planet. 

To  compare  terrestrial  volcanoes  with  solar  erup- 
tions is  like  comparing  the  modest  night-light  that  con- 
sumes a  midge  with  the  flames  of  the  fire  that  destroys 
a  town. 

The  solar  spots  vary  in  a  fairly  regular  period  of 
100 


OUR  STAR  THE 

eleven  to  twelve  years.  In  certain  years,  e.  g.9  1893, 
they  are  vast,  numerous  and  frequent;  in  other  years, 
e.  g.>  1901,  they  are  few  and  insignificant.  The  statistics 
are  very  carefully  preserved.  Here,  for  instance,  is  the 
surface  showing  sun-spots  expressed  in  millionths  of  the 
extent  of  the  visible  solar  surface: 


1800.  . 

/w 

QQ 

1898  

•  J*T 

.  27  C 

1801.  . 

<6o 

1800.  . 

....  Ill 

1802.  . 

,  .  1,214. 

1900  

7^ 

1803.  . 

,  .  1  ,464. 

1901  

20 

i8cK.  , 

074- 

1902  

62 

1806.. 

<C43 

The  years  1889  and  1901  were  minima\  the  year  1893 
a  maximum. 

It  is  a  curious  fact  that  terrestrial  magnetism  and 
the  boreal  auroras  exhibit  an  oscillation  parallel  to 
that  of  the  solar  spots,  and  apparently  the  same  occurs 
with  regard  to  temperature. 

We  must  regard  our  sun  as  a  globe  of  gas  in  a  state 
of  combustion,  burning  at  high  temperature,  and  giving 
off  a  prodigious  amount  of  heat  and  light.  The  dazzling 
surface  of  this  globe  is  called  a  photosphere  (light  sphere). 
It  is  in  perpetual  motion,  like  the  waves  of  an  ocean 
of  fire,  whose  roseate  and  transparent  flames  measure 

101 


ASTRONOMY  FOR  AMATEURS 

some  15,000  kilometers  (9,300  miles)  in  height.  This 
stratum  of  rose-colored  flames  has  received  the  name  of 
chromosphere  (color  sphere).  It  is  transparent;  it  is 
not  directly  visible,  but  is  seen  only  during  the  total 
eclipses  of  the  Sun,  when  the  dazzling  disk  of  that 
luminary  is  entirely  concealed  by  the  Moon;  or  with 
the  aid  of  the  spectroscope.  The  part  of  the  Sun  that 
we  see  is  its  luminous  surface,  or  photosphere. 

From  this  agitated  surface  there  is  a  constant 
ejection  of  gigantic  eruptions,  immense  jets  of  flame, 
geysers  of  fire,  projected  at  a  terrific  speed  to  prodig- 
ious heights. 

For  years  astronomers  were  greatly  perplexed  as  to 
the  nature  of  these  incandescent  masses,  known  as 
prominences,  which  shot  out  like  fireworks,  and  were 
only  visible  during  the  total  eclipses  of  the  Sun.  But 
now,  thanks  to  an  ingenious  invention  of  Janssen  and 
Lockyer,  these  eruptions  can  be  observed  every  day 
in  the  spectroscope,  and  have  been  registered  since 
1868,  more  particularly  in  Rome  and  in  Catania,  where 
the  Society  of  Spectroscopists  was  founded  with  this 
especial  object,  and  publishes  monthly  bulletins  in 
statistics  of  the  health  of  the  Sun. 

These  prominences  assume  all  imaginable  forms,  and 
often  resemble  our  own  storm-clouds;  they  rise  above 
the  chromosphere  with  incredible  velocity,  often  ex- 

IO2 


OUR  STAR  THE  SUN 

ceeding  200  kilometers  (124  miles)  per  second,  and  are 
carried  up  to  the  amazing  height  of  300,000  kilometers 
(186,000  miles). 

The  Sun  is  surrounded  with  these  enormous  flames 


FIG.  31. — Rose-colored  solar  flames  228,000  kilometers  (14!,- 
500  miles)  in  height,  /'.  e. ,  1 8  times  the  diameter  of  the  Earth. 

on  every  side;  sometimes  they  shoot  out  into  space 
like  splendid  curving  roseate  plumes;  at  others  they 
rear  their  luminous  heads  in  the  Heavens,  like  the 

103 


ASTRONOMY  FOR  AMATEURS 

cleft  and  waving  leaves  of  giant  palm-trees.  Having 
illustrated  a  remarkable  type  of  solar  spot,  it  is  interest- 
ing to  submit  to  the  reader  a  precise  observation  of 
these  curious  solar  flames.  That  reproduced  here  was 
observed  in  Rome,  January  30,  1885.  It  measured 
228,000  kilometers  (141,500  miles)  in  height,  eighteen 
times  the  diameter  of  the  earth  (represented  alongside 
in  its  relative  magnitude).  (Fig.  31.) 

Solar  eruptions  have  been  seen  to  reach,  in  a  few 
minutes,  a  height  of  more  than  100,000  kilometers 
(62,000  miles),  and  then  to  fall  back  in  a  flaming  torrent 
into  that  burning  and  inextinguishable  ocean. 

Observation,  in  conjunction  with  spectral  analysis, 
shows  these  prominences  to  be  due  to  formidable  ex- 
plosions produced  within  the  actual  substance  of  the 
Sun,  and  projecting  masses  of  incandescent  hydrogen 
into  space  with  considerable  force. 

Nor  is  this  all.  During  an  eclipse  one  sees  around 
the  black  disk  of  the  Moon  as  it  passes  in  front  of  the 
Sun  and  intercepts  its  light,  a  brilliant  and  rosy  aureole 
with  long,  luminous,  branching  feathers  streaming  out, 
like  aigrettes,  which  extend  a  very  considerable  distance 
from  the  solar  surface.  This  aureole,  the  nature  of 
which  is  still  unknown  to  us,  has  received  the  name  of 
corona.  It  is  a  sort  of  immense  atmosphere,  extremely 
rarefied.  Our  superb  torch,  accordingly,  is  a  brazier 

104 


OUR  STAR  THE  SUN 

of  unparalleled  activity — a  globe  of  gas,  agitated  by 
phenomenal  tempests  whose  flaming  streamers  extend 
afar.  The  smallest  of  these  flames  is  so  potent  that  it 
would  swallow  up  our  world  at  a  single  breath,  like  the 
bombs  shot  out  by  Vesuvius,  that  fall  back  within  the 
crater. 

What  now  is  the  real  heat  of  this  incandescent  focus  ? 
The  most  accurate  researches  estimate  the  temperature 
of  the  surface  of  the  Sun  at  7,000°  C.  The  internal 
temperature  must  be  considerably  higher.  A.  crucible 
of  molten  iron  poured  out  upon  the  Sun  would  be  as  a 
stream  of  ice  and  snow. 

We  can  form  some  idea  of  this  calorific  force  by 
making  certain  comparisons.  Thus,  the  heat  given  out 
appears  to  be  equal  to  that  which  would  be  emitted  by 
a  colossal  globe  of  the  same  dimensions  (that  is,  as 
voluminous  as  twelve  hundred  and  eighty  thousand 
terrestrial  globes),  entirely  covered  with  a  layer  of  in- 
candescent coal  28  kilometers  (18  miles)  in  depth,  all 
burning  at  equal  combustion.  The  heat  emitted  by 
the  Sun,  at  each  second,  is  equal  to  that  which  would 
result  from  the  combustion  of  eleven  quadrillions  six 
hundred  thousand  milliards  of  tons  of  coal,  all  burning 
together.  This  same  heat  would  bring  to  the  boil  in  an 
hour,  two  trillions  nine  hundred  milliards  of  cubic 
kilometers  of  water  at  freezing-point. 

105 


ASTRONOMY  FOR  AMATEURS 

Our  little  planet,  gravitating  at  149,000,000  kilo- 
meters (93,000,000  miles)  from  the  Sun,  arrests  on  the 
way,  and  utilizes,  only  the  half  of  a  milliard  part  of  this 
total  radiation. 

How  is  this  heat  maintained  ?  One  of  the  prin- 
cipal causes  of  the  heat  of  the  Sun  is  its  condensation. 
According  to  all  probabilities,  the  solar  globe  repre- 
sents for  us  the  nucleus  of  a  vast  nebula,  that  extended 
in  primitive  times  beyond  the  orbit  of  Neptune,  and 
which  in  its  contraction  has  finally  produced  this  central 
focus.  In  virtue  of  the  law  of  transformation  of  motion 
into  heat,  this  condensation,  which  has  not  yet  reached 
its  limit,  suffices  to  raise  this  colossal  globe  to  its  level 
of  temperature,  and  to  maintain  it  there  for  millions  of 
years.  In  addition,  a  substantial  number  of  meteors 
is  forever  falling  into  it.  This  furnace  is  a  true  pande- 
monium. 

The  Sun  weighs  three  hundred  and  twenty-four 
thousand  times  more  than  the  Earth — that  is  to  say, 
eighteen  hundred  and  seventy  octillions  of  kilograms: 

1,870,000,000,000,000,000,000,000,000,000 
(1,842,364,532,019,704,433,497,536,945  tons). 

In  Chapter  XI  we  shall  explain  the  methods  by  which 
it  has  been  found  possible  to  weigh  the  Sun  and  deter- 
mine its  exact  distance. 


106 


OUR  STAR  THE  SUN 

I  trust  these  figures  will  convey  some  notion  of  the 
importance  and  nature  of  the  Sun,  the  stupendous  orb 
on  whose  rays  our  very  existence  depends.  Its  apparent 
dimension  (which  is  only  half  a  degree,  32',  and  would 
be  hidden  from  sight,  like  that  of  the  full  moon,  which 
is  about  the  same,  by  the  tip  of  the  little  finger  held 
out  at  arm's  length),  represents,  as  we  have  seen,  a  real 
dimension  that  is  colossal,  t.  e.,  1,383,000  kilometers 
(more  than  857,000  miles),  and  this  is  owing  to  the 
enormous  distance  that  separates  us  from  it.  This 
distance  of  149,000,000  kilometers  (93,000,000  miles) 
is  sufficiently  hard  to  appreciate.  Let  us  say  that 
11,640  terrestrial  globes  would  be  required  to  throw  a 
bridge  from  here  to  the  Sun,  while  30  would  suffice  from 
the  Earth  to  the  Moon.  The  Moon  is  388  times  nearer 
to  us  than  the  Sun.  We  may  perhaps  conceive  of  this 
distance  by  calculating  that  a  train,  moving  at  constant 
speed  of  I  kilometer  (0.6214  mile)  a  minute,  would  take 
149,000,000  minutes,  that  is  to  say  103,472  days,  or 
283  years,  to  cross  the  distance  that  separates  us  from 
this  orb.  Given  the  normal  duration  of  life,  neither 
the  travelers  who  set  out  for  the  Sun,  nor  their  children, 
nor  their  grandchildren,  would  arrive  there:  only  the 
seventh  generation  would  reach  the  goal,  and  only  the 
fourteenth  could  bring  us  back  news  of  it. 

Children  often  cry  for  the  Moon.  If  one  of  these 
107 


ASTRONOMY  FOR  AMATEURS 

inquisitive  little  beings  could  stretch  out  its  arms  to 
touch  the  Sun,  and  burn  its  fingers  there,  it  would  not 
feel  the  burn  for  one  hundred  and  sixty-seven  years 
(when  it  would  no  longer  be  an  infant),  for  the  nervous 
impulse  of  sensation  can  only  be  transmitted  from  the 
ends  of  the  fingers  to  the  brain  at  a  velocity  of  28  meters 
per  second. 

'Tis  long.  A  cannon-ball  would  reach  the  Sun  in 
ten  years.  Light,  that  rapid  arrow  that  flies  through 
space  at  a  velocity  of  300,000  kilometers  (186,000  miles 
per  second),  takes  only  eight  minutes  seventeen  seconds 
to  traverse  this  distance. 

This  brilliant  Sun  is  not  only  sovereign  of  the 
Earth;  he  is  also  the  head  of  a  vast  planetary  system. 

The  orbs  that  circle  round  the  Sun  are  opaque  bodies, 
spherical  in  shape,  receiving  their  light  and  heat  from 
the  central  star,  on  which  they  absolutely  depend.  The 
name  of  planets  given  to  them  signifies  "wandering" 
stars.  If  you  observe  the  Heavens  on  a  fine  starry  night, 
and  are  sufficiently  acquainted  with  the  principal  stars 
of  the  Zodiac  as  described  in  a  preceding  chapter,  you 
may  be  surprised  on  certain  evenings  to  see  the  figure 
of  some  zodiacal  constellation  slightly  modified  by  the 
temporary  presence  of  a  brilliant  orb  perhaps  surpassing 
in  its  luminosity  the  finest  stars  of  the  first  magnitude. 

108 


OUR  STAR  THE  SUN 

If  you  watch  this  apparition  for  some  weeks,  and 
examine  its  position  carefully  in  regard  to  the  adjacent 
stars,  you  will  observe  that  it  changes  its  position  more 
or  less  slowly  in  the  Heavens.  These  wandering  orbs, 
or  planets,  do  not  shine  with  intrinsic  light;  they  are 
illuminated  by  the  Sun. 

The  planets,  in  effect,  are  bodies  as  opaque  as  the 
Earth,  traveling  round  the  God  of  Day  at  a  speed  pro- 
portional to  their  distance.  They  number  eight  prin- 
cipal orbs,  and  may  be  divided  into  two  quite  distinct 
groups  by  which  we  may  recognize  them:  the  first  com- 
prises four  planets,  of  relatively  small  dimensions  in 
comparison  with  those  of  the  second  group,  which  are 
so  voluminous  that  the  least  important  of  them  is  larger 
than  the  other  four  put  together. 

In  order  of  distance  from  the  Sun,  we  first  encounter: 

MERCURY,  VENUS,  THE  EARTH,  AND  MARS 

These  are  the  worlds  that  are  nearest  to  the  orb  of 
day. 

The  four  following,  and  much  more  remote,  are, 
still  in  order  of  distance: 

JUPITER,  SATURN,  URANUS,  AND  NEPTUNE 

This  second  group  is  separated  from  the  first  by  a 
vast  space  occupied  by  quite  a  little  army  of  minute 
planets,  tiny  cosmic  bodies,  the  largest  of  which  meas- 

109 


ASTRONOMY  FOR  AMATEURS 

ures  little  more  than  100  kilometers  (62  miles)  in  di- 
ameter, and  the  smallest  some  few  miles  only. 

The  planets  which  form  these  three  groups  represent 
the  principal  members  of  the  solar  family.  But  the  Sun 
is  a  patriarch,  and  each  of  his  daughters  has  her  own 
children  who,  while  obeying  the  paternal  influence  of 
the  fiery  orb,  are  also  obedient  to  the  world  that  governs 
them.  These  secondary  asters,  or  satellites,  follow  the 
planets  in  their  course,  and  revolve  round  them  in  an 
ellipse,  just  as  the  others  rotate  round  the  Sun.  Every 
one  knows  the  satellite  of  the  Earth,  the  Moon.  All 
the  other  planets  of  our  system  have  their  own  moons, 
some  being  even  more  favored  than  ourselves  in  this 
respect,  and  having  several.  Mars  has  two;  Jupiter, 
five;  Saturn,  eight;  Uranus,  four;  and  Neptune,  one 
(at  least  as  yet  discovered). 

In  order  to  realize  the  relations  between  these  worlds, 
we  must  appreciate  their  distances  by  arranging  them 
in  a  little  table: 

Distance  in  Distance  in 
Millions  of  Millions  of 
Kilometers.  Miles. 

Mercury 57  35 

Venus ....  108  67 

The  Earth 149  93 

Mars 226  140 

Jupiter 775  4&I 

Saturn 1,421  882 

Uranus. 2,831  1,755 

Neptune 4,470  2,77* 

110 


OUR  STAR  THE  SUN 

The  Sun  is  at  the  center  (or,  more  properly  speaking, 
at  the  focus,  for  the  planets  describe  an  ellipse)  of  this 
system,  and  controls  them.  Neptune  is  thirty  times 
farther  from  the  Sun  than  the  Earth.  These  disparities 
of  distance  produce  a  vast  difference  in  the  periods  of 
the  planetary  revolutions;  for  while  the  Earth  revolves 
round  the  Sun  in  a  year,  Venus  in  224  days,  and  Mercury 
in  88,  Mars  takes  nearly  2  years  to  accomplish  his 
journey,  Jupiter  12  years,  Saturn  29,  Uranus  84,  and 
Neptune  165. 

Even  the  planets  and  their  moons  do  not  represent 
the  Sun's  complete  paternity.  There  are  further,  in 
the  solar  republic,  certain  vagabond  and  irregular  orbs 
that  travel  at  a  speed  that  is  often  most  immoderate, 
occasionally  approaching  the  Sun,  not  to  be  consumed 
therein,  but,  as  it  appears,  to  draw  from  its  radiant 
source  the  provision  of  forces  necessary  for  their  peri- 
grinations  through  space.  These  are  the  Comets,  which 
pursue  an  extremely  elongated  orbit  round  the  Sun,  to 
which  at  times  they  approximate  very  closely,  at  other 
times  being  excessively  distant. 

And  now  to  recapitulate  our  knowledge  of  the  Solar 
Empire.  In  the  first  place,  we  see  a  colossal  globe  of  fire 
dominating  and  governing  the  worlds  that  belong  to 
him.  Around  him  are  grouped  planets,  in  number  eight 
principal,  formed  of  solid  and  obscure  matter,  gravi- 

III 


ASTRONOMY  FOR  AMATEURS 

tating  round  the  central  orb.  Other  secondary  orbs,  the 
satellites,  revolve  round  the  planets,  which  keep  them 
within  the  sphere  of  their  attraction.  And  lastly,  the 
comets,  irregular  celestial  bodies,  track  the  whole 
extent  of  the  great  solar  province.  To  these  might  be 
added  the  whirlwinds  of  meteors,  as  it  were  disaggre- 
gated comets,  which  also  circle  round  the  Sun,  and  give 
origin  to  shooting  stars,  when  they  come  into  collision 
with  the  Earth. 

Having  now  a  general  idea  of  our  celestial  family,  and 
an  appreciation  of  the  potent  focus  that  controls  it,  let 
us  make  direct  acquaintance  with  the  several  members 
of  which  it  is  composed. 


112 


CHAPTER  V 

THE    PLANETS 

A. — MERCURY,  VENUS,  THE  EARTH,   MARS 

AND  now  we  are  in  the  Solar  System,  at  the  center, 
or,  better,  at  the  focus  of  which  burns  the  immense  and 
dazzling  orb.  We  have  appreciated  the  grandeur  and 
potency  of  the  solar  globe,  whose  rays  spread  out  in  active 
waves  that  bear  a  fecundating  illumination  to  the  worlds 
that  gravitate  round  him;  we  have  appreciated  the  dis- 
tance that  separates  the  Sun  from  the  Earth,  the  third 
of  the  planets  retained  within  his  domain,  or  at  least  I 
trust  that  the  comparisons  of  the  times  required  by 
certain  moving  objects  to  traverse  this  distance  have 
enabled  us  to  conceive  it. 

We  said  that  the  four  planets  nearest  to  the  Sun  are 
Mercury,  at  a  distance  of  57  million  kilometers  (35,000,- 
ooo  miles);  Venus,  at  108  million  (67,000,000  miles); 
the  Earth,  at  149  million  (93,000,000  miles);  and  Mars 
at  226  million  (140,000,000  miles).  Let  us  begin  our 
planetary  journey  with  these  four  stationSo 


ASTRONOMY  FOR  AMATEURS 


MERCURY 

A  little  above  the  Sun  one  sometimes  sees,  now  in 
the  West,  in  the  lingering  shimmer  of  the  twilight,  now 
in  the  East,  when  the  tender  roseate  dawn  announces 
the  advent  of  a  clear  day,  a  small  star  of  the  first  mag- 
nitude which  remains  but  a  very  short  time  above  the 
horizon,  and  then  plunges  back  into  the  flaming  sun. 
This  is  Mercury,  the  agile  and  active  messenger  of 
Olympus,  the  god  of  eloquence,  of  medicine,  of  com- 
merce, and  of  thieves.  One  only  sees  him  furtively, 
from  time  to  time,  at  the  periods  of  his  greatest  elonga- 
tions, either  after  the  setting  or  before  the  rising  of  the 
radiant  orb,  when  he  presents  the  aspect  of  a  somewhat 
reddish  star. 

This  planet,  like  the  others,  shines  only  by  the  re- 
flection of  the  Sun  whose  illumination  he  receives,  and 
as  he  is  in  close  juxtaposition  with  it,  his  light  is  bright 
enough,  though  his  volume  is  inconsiderable.  He  is 
smaller  than  the  Earth.  His  revolution  round  the  Sun 
being  accomplished  in  about  three  months,  he  passes 
rapidly,  in  a  month  and  a  half,  from  one  side  to  the 
other  of  the  orb  of  day,  and  is  alternately  a  morning 
and  an  evening  star.  The  ancients  originally  regarded 
it  as  two  separate  planets;  but  with  attentive  obser- 

114 


THE  PLANETS 

vation,  they  soon  perceived  its  identity.  In  our  some* 
what  foggy  climates,  it  can  only  be  discovered  once  or 
twice  a  year,  and  then  only  by  looking  for  it  according 
to  the  indications  given  in  the  astronomic  almanacs. 


Mars 


as:  days 


FIG.  32. — Orbits  of  the  four  Planets  nearest  to  the  Sun. 

Mercury  courses  round  the  Sun  at  a  distance  oi 
57,000,000  kilometers  (35,000,000  miles),  and  accom- 
plishes his  revolution  in  87  days,  23  hours,  15  minutes; 
f.  *.,  2  months,  27  days,  23  hours,  or  a  little  less  than 
three  of  our  months.  If  the  conditions  of  life  are  the 
9  115 


ASTRONOMY  FOR  AMATEURS 

same  there  as  here,  the  existence  of  the  Mercurians 
must  be  four  times  as  short  as  our  own.  A  youth  of 
twenty,  awaking  to  the  promise  of  the  life  he  is  just 
beginning  in  this  world,  is  an  octogenarian  in  Mercury. 


Neptune 


Uranus. 


Saturn 


FIG.  33. — Orbits  of  the  four  Planets  farthest  from  the  Sun. 

There  the  fair  sex  would  indeed  be  justified  in  bewailing 
the  transitory  nature  of  life,  and  might  regret  the  years 
that  pass  too  quickly  away.  Perhaps,  however,  they  are 
more  philosophic  than  with  us. 

116 


THE  PLANETS 


The  orbit  of  Mercury,  which  of  course  is  within  that 
of  the  Earth,  is  not  circular,  but  elliptical,  and  very 
eccentric,  so  elongated  that  at  certain  times  of  the  year 
this  planet  is  extremely  remote  from  the  solar  focus,  and 
receives  only  half  as  much  heat  and  light  as  at  the  op- 
posite period;  and,  in  consequence,  his  distance  from  the 
Earth  varies  con- 
siderably. 

This  globe 
exhibits  phases, 
discovered  in  the 
seventeenth  cen- 
tury by  Galileo, 
which  recall 
those  of  the 
Moon.  They  are 
due  to  the  mo- 
tions  of  the 
planet  round  the 
Sun,  and  are  invisible  to  the  unaided  eye,  but  with  even 
a  small  instrument,  one  can  follow  the  gradations  and 
study  Mercury  under  every  aspect.  Sometimes,  again, 
he  passes  exactly  in  front  of  the  Sun,  and  his  disk  is 
projected  like  a  black  point  upon  the  luminous  surface 
of  the  flaming  orb.  This  occurred,  notably,  on  May  10, 
1891,  and  November  10,  1894;  and  the  phenomenon 

117 


FIG.  34. — Mercury  near  quadrature. 


ASTRONOMY  FOR  AMATEURS 

will  recur  on   November    12,   1907,  and  November  6, 

IQI4- 

Mercury  is  the  least  of  all  the  worlds  in  our  system 
(with  the  exception  of  the  cosmic  fragments  that  circulate 
between  the  orbit  of  Mars  and  that  of  Jupiter).  His 
volume  equals  only  Tf  ¥  that  of  the  Earth.  His  diameter, 
in  comparison  with  that  of  our  planet,  is  in  the  ratio  of 
373  to  1,000  (a  little  more  than  YZ]  and  measures  4,750 
kilometers  (2,946  miles).  His  density  is  the  highest  of 
all  the  worlds  in  the  great  solar  family,  and  exceeds  that 
of  our  Earth  by  about  /<3;  but  weight  there  is  less  by 
almost  YZ. 

Mercr.ry  is  enveloped  in  a  very  dense,  thick  atmos- 
phere, which  doubtless  sensibly  tempers  the  solar  heat, 
for  the  Sun  exhibits  to  the  Mercurians  a  luminous  disk 
about  seven  times  more  extensive  than  that  with  which 
we  are  familiar  on  the  Earth,  and  when  Mercury  is  at 
perihelion  (that  is,  nearest  to  the  Sun),  his  inhabitants 
receive  ten  times  more  light  and  heat  than  we  obtain  at 
midsummer.  In  all  probability,  it  would  be  impossible 
for  us  to  set  foot  on  this  planet  without  being  shattered 
by  a  sunstroke. 

Yet  we  may  well  imagine  that  Nature's  fecundity  can 
have  engendered  beings  there  of  an  organization  different 
from  our  own,  adapted  to  an  existence  in  the  proximity 
of  fire.  What  magnificent  landscapes  may  there  be 


THE  PLANETS 

adorned   with    the    luxuriant  vegetation    that  develops 
rapidly  under  an  ardent  and  generous  sun  ? 


FIG.  35. — The  Earth  viewed  from  Mercury. 
Observations    of   Mercury    are    taken    under    great 
difficulties,  just  because  of  the  immediate  proximity  of 

119 


ASTRONOMY  FOR  AMATEURS 

the  solar  furnace;  yet  some  have  detected  patches  that 
might  be  seas.  In  any  case,  these  observations  are  con- 
tradictory and  uncertain. 

Up  to  the  present  it  has  been  impossible  to  determine 
the  duration  of  the  rotation.  Some  astronomers  even 
think  that  the  Sun's  close  proximity  must  have  produced 
strong  tides,  that  would,  as  it  were,  have  immobilized 
the  globe  of  Mercury,  just  as  the  Earth  has  immobilized 
the  Moon,  forcing  it  perpetually  to  present  the  same 
side  to  the  Sun.  From  the  point  of  view  of  habitation, 
this  situation  would  be  somewhat  peculiar;  perpetual 
day  upon  the  illumined  half,  perpetual  night  upon  the 
other  hemisphere,  and  a  fairly  large  zone  of  twilight  be- 
tween the  two.  Such  a  condition  would  indeed  be  differ- 
ent from  the  succession  of  terrestrial  days  and  nights. 

As  seen  from  Mercury,  the  Earth  we  inhabit  would 
shine  out  in  the  starry  sky  *  as  a  magnificent  orb  of  first 

*  The  author  has  endeavored  on  the  plates  to  represent  the  aspect  of  the 
Earth  in  the  starry  sky  of  Mercury,  Venus,  and  Mars;  but  in  all  representa- 
tions of  this  kind  the  stars  are  necessarily  made  too  large.  By  calculation 
the  diameters  of  the  Earth  and  Moon  as  seen  from  the  planets,  and  their 

distances,  are  as  follows: 

Diameter  of     Diameter  of  Distance 

the  Earth.       the  Moon.         Earth-Moon. 

Of  Mercury  (opposition) 20"  8"  871" 

Of  Venus  (opposition) 64"  17"  1,928'' 

Of  Mars  (quadrature) 15"  4"  464" 

Of  Jupiter  (quadrature) -$"$  o"i  105" 

These  aspects  will  be  appreciated  if  we  rememoer  that  the  distance  of  the 
components  of  e  Lyre  =  207",  that  of  Atlas  in  Pleione  =  301',  and  that  of 
the  stars  Mizar  and  Alcor  =  708". 

I2O 


THE  PLANETS 

magnitude,  with  the  Moon  alongside,  a  faithful  little 
companion.  They  should  form  a  fine  double  star,  the 
Earth  being  a  brilliant  orb  of  first  magnitude,  and  the 
Moon  of  third,  a  charming  couple,  and  admired  doubtless 
as  an  enchanted  and  privileged  abode. 

It  is  at  midnight  during  the  oppositions  of  the  Earth 
with  the  Sun  that  our  planet  is  the  most  beautiful  and 
brilliant,  as  is  Jupiter  for  ourselves.  The  constellations 
are  the  same,  viewed  from  Mercury  or  from  the  Earth. 

But  is  this  little  solar  planet  inhabited  ?  We  do  not 
yet  know.  We  can  only  reply:  why  not? 


VENUS 

When  the  sunset  atmosphere  is  crimson  with  the 
glorious  rays  of  the  King  of  Orbs,  and  all  Nature  as- 
sumes the  brooding  veil  of  twilight,  the  most  indifferent 
eyes  are  often  attracted  and  captivated  by  the  presence 
of  a  star  that  is  almost  dazzling,  and  illuminates  with 
its  white  and  limpid  light  the  heavens  darkened  by  the 
disappearance  of  the  God  of  Day. 

Hail,  Venus,  Queen  of  the  Heavens!  the  "  Shepherd's 
Star,"  gentle  mother  of  the  loves,  goddess  of  beauty,  eter- 
nally adored  and  cherished,  sung  and  immortalized  upon 
Earth,  by  poets  and  artists.  Her  splendid  brilliancy 
attracted  notice  from  earliest  antiquity,  and  we  find  her, 

121 


ASTRONOMY  FOR  AMATEURS 

radiant  and  charming,  in  the  works  of  the  ancients,  who 
erected  altars  to  her  and  adorned  their  poetry  with  her 
grace  and  beauty.  Homer  calls  her  Callisto  the  Beau- 
tiful; Cicero  names  her  Vesper,  the  evening  star,  and 
Lucifer,  the  star  of  the  morning — for  it  was  with  this 
divinity  as  with  Mercury.  For  a  long  while  she  was 
regarded  as  two  separate  planets,  and  it  was  only  when 
it  came  to  be  observed  that  the  evening  and  the  morning 
star  were  always  in  periodic  succession,  that  the  identity 
of  the  orb  was  recognized. 

Her  radiant  splendor  created  her  mythological  per- 
sonality, just  as  the  agility  of  Mercury  created  that  of 
the  messenger  of  the  gods. 

We  do  not  see  her  aerial  chariot  in  the  Heavens  drawn 
by  a  flight  of  doves  with  white  and  fluttering  wings,  but 
we  follow  the  lustrous  orb  led  on  through  space  by  solar 
attraction.  And  in  the  beautiful  evenings  when  she  is 
at  her  greatest  distance  from  our  Sun,  the  whole  world 
admires  this  white  and  dazzling  Venus  reigning  as  sov- 
ereign over  our  twilight  *  for  hours  after  sunset,  and  in 
addition  to  the  savants  who  are  practically  occupied 

*  A  few  evenings  ago,  after  observing  Venus  in  the  calm  and  silent  Heavens 
at  the  close  of  day,  my  eyes  fell  upon  a  drawing  sent  me  by  my  friend  Gustave 
Dore,  which  is  included  in  the  illustrations  of  his  wonderful  edition  of  Dante's 
Divina  Commedia.  This  drawing  seems  to  be  in  place  here,  and  1  offer  my 
readers  a  poor  reproduction  of  it,  taken  from  the  fine  engraving  in  the  book. 
Dante  and  Virgil,  in  the  peaceful  evening,  are  contemplating  lo  bel  fianeta 
ttfad  amar  conforta  (the  beautiful  planet  that  incites  to  love), 

122 


THE  PLANETS 

with  astronomy,  millions  of  eyes  are  raised  to  this  celes- 
tial splendor,  and  for  a  moment  millions  of  human  beings 


FIG.  36. — The  Evening  Star. 

feel  some  curiosity  about  the  mysteries  of  the  Infinite. 
The  brutalities  of  daily  life  would  fain  petrify  our  dreams, 
but  thought  is  not  yet  stifled  to  the  point  of  checking  all 

123 


ASTRONOMY  FOR  AMATEURS 

aspirations  after  eternal  truth,  and  when  we  gaze  at  the 
starry  sky  it  is  hard  not  to  ask  ourselves  the  nature  of 
those  other  worlds,  and  the  place  occupied  by  our  own 
planet  in  the  vast  concert  of  sidereal  harmony. 

Even  through  a  small  telescope,  Venus  offers  re- 
markable phases. 

Fig.  37  gives  some  notion  of  the  succession  of  these, 
and  of  the  planet's  variations  in  magnitude  during  its 


FIG.  37. — Successive  phases  of  Venus. 

journey  round  the  Sun.  Imagine  it  to  be  rotating  in  a 
year  of  224  days,  1 6  hours,  49  minutes,  8  seconds  at  a 
distance  of  108  million  kilometers  (67,000,000  miles), 
the  Earth  being  at  149  million  (93,000,000  miles).  Like 
Mercury,  at  certain  periods  it  passes  between  the  Sun 
and  ourselves,  and  as  its  illuminated  hemisphere  is  of 
course  turned  toward  the  orb  of  day,  we  at  those  times 
perceive  only  a  sharp  and  very  luminous  crescent.  At 

124 


THE  PLANETS 

such  periods  Venus  is  entirely,  so  to  say,  against  the  Sun, 
and  presents  to  us  her  greatest  apparent  dimension 
(Fig.  38).  Sometimes,  again,  like  Mercury,  she  passes 
immediately  in  front  of  the  Sun,  forming  a  perfectly 
round  black  spot;  this  happened  on  December  8,  1874, 
and  December  6,  1882;  and  will  recur  on  June  7,  2004, 
and  June  5,  2012  These  transits  have  been  utilized  in 
celestial  geometry  in  measuring  the  distance  of  the  Sun. 

You  will  readily  divine  that  the  distance  of  Venus 
varies  considerably  according  to  her  position  in  relation 
to  the  Earth:  when  she  is  between  the  Sun  and  ourselves 
she  is  nearest  to  our  world;  but  it  is  just  at  those  times 
that  we  see  least  of  her  surface,  because  she  exhibits  to 
us  only  a  slender  crescent.  Terrestrial  astronomers  are 
accordingly  very  badly  placed  for  the  study  of  her  phys- 
ical constitution.  The  best  observations  can  be  made 
when  she  is  situated  to  right  or  left  of  the  Sun,  and  shows 
us  about  half  her  illuminated  disk — during  the  day  for 
choice,  because  at  night  there  is  too  much  irradiation 
from  her  dazzling  light. 

These  phases  were  discovered  by  Galileo,  in  1610. 
His  observations  were  among  the  first  that  confirmed 
the  veracity  of  the  system  of  Copernicus,  affording  an 
evident  example  of  the  movement  of  the  planets  round 
the  sun.  They  are  often  visible  to  the  unaided  eye  with 
good  sight,  either  at  dusk,  or  through  light  clouds. 

125 


ASTRONOMY  FOR  AMATEURS 


Venus,  surrounded  by  a  highly  dense  and  rarefied 
atmosphere,  which  increases  the  difficulties  of  observ- 
ing her  surface,  might  be  called  the  twin  sister  of  the 
Earth,  so  similar  are  the  dimensions  of  the  two  worlds. 
But,  strange  as  it  may  seem  to  the  many  .admirers,  who 
are  ready  to  hail  in  her  an  abode  of  joy  and  happiness, 

it  is  most  prob- 
able that  this 
planet,  attract- 
ive as  she  is  at  a 
distance,  would 
be  a  less  desir- 
able habitation 
than  our  float- 
ing island.  In 
fact,  the  atmos- 
phere of  Venus 
is  perpetually 
covered  with 
cloud,  so  that  the  weather  there  must  be  always  foggy. 
No  definite  geographical  configuration  can  be  discovered 
on  her,  despite  the  hopes  of  the  eighteenth-century  astron- 
omers. We  are  not  even  sure  that  she  rotates  upon  her- 
self, so  contradictory  are  the  observations,  and  so  hard 
is  it  to  distinguish  anything  clearly  upon  her  surface.  A 
single  night  of  observation  suffices  to  show  the  rotation 

126 


FIG.  38. — Venus  at  greatest  brilliancy. 


THE  PLANETS 

of  Mars  or  of  Jupiter;  but  the  beautiful  Evening  Star 
remains  obstinately  veiled  from  our  curiosity. 

Several  astronomers,  and  not  the  least  considerable, 
think  that  the  tides  produced  by  the  Sun  upon  her  seas, 
or  globe  in  its  state  of  pristine  fluidity,  must  have  been 
strong  enough  to  seize  a,nd  fix  her,  as  the  Earth  did  for 
the  Moon,  thus  obliging  her  to  present  always  the  same 
face  to  the  Sun.  Certain  telescopic  observations  would 
even  seem  to  confirm  this  theoretical  deduction  from  the 
calculations  of  celestial  mechanics. 

The  author  ventures  to  disagree  with  this  opinion, 
its  apparent  probability  notwithstanding,  because  he  has 
invariably  received  a  contrary  impression  from  all  his 
telescopic  observations.  He  has  quite  recently  (spring 
of  1903)  repeated  these  observations.  Choosing  a  re- 
markably clear  and  perfectly  calm  atmosphere,  he 
examined  the  splendid  planet  several  times  with  great 
attention  in  the  field  of  the  telescope.  The  right  or 
eastern  border  (reversed  image)  was  dulled  by  the  at- 
mosphere of  Venus;  this  is  the  line  of  separation  between 
day  and  night.  Beneath,  at  the  extreme  northern  edge, 
he  was  attracted  on  each  occasion  by  a  small  white 
patch,  a  little  whiter  than  the  rest  of  the  surface  of  the 
planet,  surrounded  by  a  light-gray  penumbra,  giving  the 
exact  effect  of  a  polar  snow,  very  analogous  to  that 
observed  at  the  poles  of  Mars.  To  the  author  this  white 

127 


ASTRONOMY  FOR  AMATEURS 

spot  on  the 'boreal  horn  of  Venus  does  not  appear  to 
be  due  to  an  effect  of  contrast,  as  has  sometimes  been 
supposed. 

Now,  if  the  globe  of  Venus  has  poles,  it  must  turn 
upon  itself. 

Unfortunately  it  has  proved  impossible  to  distinguish 
any  sign  upon  the  disk,  indicative  of  the  direction  and 
speed  of  its  rotary  movement,  although  these  observa- 
tions were  made,  with  others,  under  excellent  conditions. 
— Three  o'clock  in  the  afternoon,  brilliant  sun,  sky 
clear  blue,  the  planet  but  little  removed  from  the 
meridian — at  which  time  it  is  less  dazzling  than  in  the 
evening. 

There  is  merely  the  impression;  but  it  is  so  definite 
as  to  prevent  the  author  from  adopting  the  new  hypoth- 
esis, in  virtue  of  which  the  planet,  as  it  gravitates 
round  the  Sun,  presents  always  the  same  hemisphere. 

If  this  hypothesis  were  a  reality,  Venus  would  cer- 
tainly be  a  very  peculiar  world.  Eternal  day  on  the  one 
side;  eternal  night  on  the  other.  Maximum  light  and 
heat  at  the  center  of  the  hemisphere  perpetually  turned 
to  the  Sun;  maximum  cold  and  center  of  night  at,  the 
antipodes.  This  icy  hemisphere  would  possibly  be 
uninhabitable,  but  the  resources  of  Nature  are  so  pro- 
digious, and  the  law  of  Life  is  so  imperious,  so  persist- 
ent, under  the  most  disadvantageous  and  deplorable 

128 


THE  PLANETS 

terrestrial  conditions,  that  it  would  be  transcending  our 
rights  to  declare  an  impossibility  of  existence,  even  in 
this  eternal  night.  The  currents  of  the  atmosphere 
would  no  doubt  suffice  to  set  up  perpetual  changes  of 
temperature  between  the  two  hemispheres,  in  compari- 
son with  which  our  trade-winds  would  be  the  lightest  of 
breezes. 

Yes,  mystery  still  reigns  upon  this  adjacent  earth, 
and  the  most  powerful  instruments  of  the  observatories 
of  the  whole  world  have  been  unable  to  solve  it.  All 
we  know  is  that  the  diameter,  surface,  volume  and  mass 
of  this  planet,  and  its  weight  at  the  surface,  do  not  differ 
sensibly  from  those  that  characterize  our  own  globe  : 
that  this  planet  is  sister  to  our  own,  and  of  the  same 
order,  hence  probably  formed  of  the  same  elements. 
We  further  know  that,  as  seen  from  Venus  (Fig.  39),  the 
Earth  on  which  we  live  is  a  magnificent  star,  a  double 
orb  more  brilliant  even  than  when  viewed  from  Mer- 
cury. It  is  a  dazzling  orb  of  first  magnitude,  accom- 
panied by  its  moon,  a  star  of  the  second  and  a  half 
magnitude. 

And  thus  the  worlds  float  on  in  space,  distant  sym- 
bols of  hopes  not  realized  on  any  one  of  them,  all  at 
different  stages  of  their  degree  of  evolution,  repre- 
senting an  ever-growing  progress  in  the  sequence  of 
the  ages. 

129 


ASTRONOMY  FOR  AMATEURS 


FIG.  39. — The  Earth  viewed  from  Venus. 

When  we  contemplate  this  radiant  Venus,  it  is  diffi- 
cult, even  if  we  can  not  form  any  definite  idea  as  to  her 
actual  state  as  regards  habitation,  to  assume  that  she 

130 


THE  PLANETS 

must  be  a  dreary  desert,  and  not,  on  the  contrary,  to  hail 
in  her  a  celestial  land,  differing  more  or  less  from  our 
own  dwelling-place,  travailing  with  her  sisters  in  the 
accomplishment  of  the  general  plan  of  Nature. 

Such  are  the  characteristic  features  of  our  celestial 
neighbor.  In  quitting  her,  we  reach  the  Earth,  which 
comes  immediately  next  her  in  order  of  distance,  149 
million  kilometers  (93,000,000  miles)  from  the  Sun,  but 
as  we  shall  devote  an  entire  chapter  to  our  own  planet, 
we  will  not  halt  at  this  point,  but  cross  in  one  step  the 
distance  that  separates  Mars  from  Venus. 

Let  us  only  remark  in  passing,  that  our  planet  is  the 
largest  of  the  four  spheres  adjacent  to  the  Sun.  Here 
are  their  comparative  diameters: 

The  Earth  =  i.  In  Kilometers.  In  Miles. 

Mercury 0.373  4*75°  2»946 

Venus 0.999  I2>73°  7*894 

Earth i.ooo  12>74a  7>926 

Mars 0.528  6,728  4,172 

It  will  be  seen  that  Venus  is  almost  identical  with 
the  Earth. 

MARS 

Two  hundred  and  twenty-six  millions  of  kilometers 
(140,000,000  miles)  from  the  Sun  is  the  planet  Mars, 
gravitating  in  an  orbit  exterior  to  that  which  the  Earth 
takes  annually  round  the  same  center. 
10  131 


ASTRONOMY  FOR  AMATEURS 

Unfortunate  Mars!  What  evil  fairy  presided  at  his 
birth  ?  From  antiquity,  all  curses  seem  to  have  fallen 
upon  him,  He  is  the  god  of  war  and  of  carnage,  the 
protector  of  armies,  the  inspirer  of  hatred  among  the 
peoples,  it  is  he  who  pours  out  the  blood  of  Humanity  in 
international  hecatombs.  Here,  again,  as  in  the  case  of 
Mercury  and  Venus,  the  appearance  has  originated  the 
idea.  Mars,  in  fact,  burns  like  a  drop  of  blood  in  the 
depths  of  the  firmament,  and  it  is  this  ruddy  color  that 
inspired  its  name  and  attributes,  just  as  the  dazzling 
whiteness  of  Venus  made  her  the  goddess  of  love  and 
beauty.  Why,  indeed,  should  the  origins  of  mythology 
be  sought  elsewhere  than  in  astronomy  ? 

While  Humanity  was  attributing  to  the  presumptive 
influence  of  Mars  the  defects  inherent  in  its  own  terres- 
trial nature,  this  world,  unwitting  of  our  sorrows,  pur- 
sued the  celestial  path  marked  out  for  it  in  space  by 
destiny. 

This  planet  is,  as  we  have  said,  the  first  encountered 
after  the  Earth.  Its  orbit  is  very  elongated,  very  eccen- 
tric. Mars  accomplishes  it  in  a  period  of  I  year,  321 
days,  22  hours,  /.  e.,  i  year,  10  months,  21  days,  or 
687  days.  The  velocity  of  its  transit  is  23  kilometers 
(14.5  miles)  per  second;  that  of  the  Earth  is  30  (19  miles). 
Our  planet,  traveling  through  space  at  an  average  dis- 
tance of  149  million  kilometers  (93,000,000  miles)  from 

I32 


THE  PLANETS 

the  central  focus,  is  separated  from  Mars  by  an  average 
distance  of  76  million  kilometers  (47,000,000  miles);  but 
as  its  orbit  is  equally  elliptic  and  elongated  it  follows 
that  at  certain  epochs  the  two  planets  approach  one 
another  by  something  less  than  60  million  kilometers 
(37,000,000  miles).  These  are  the  periods  selected  for 
making  the  best  observations  upon  our  neighbor  of  the 
ruddy  rays.  The  oppositions  of  Mars  arrive  about 
every  twenty-six  months,  but  the  periods  of  its  greatest 
proximity,  when  this  planet  approaches  to  within 
56  million  kilometers  (34,700,000  miles)  of  the  Earth, 
occur  only  every  fifteen  years. 

Mars  is  then  passing  perihelion,  while  our  world  is 
at  aphelion  (or  greatest  distance  from  the  Sun).  At 
such  epochs  this  globe  presents  to  us  an  apparent 
diameter  63  times  smaller  than  that  of  the  Moon,  z.  <?.,  a 
telescope  that  magnifies  63  times  would  show  him  to  us 
of  the  same  magnitude  as  our  satellite  viewed  with  the 
unaided  eye,  and  an  instrument  that  magnified  630  times 
would  show  him  ten  times  larger  in  diameter. 

In  dimensions  he  differs  considerably  from  our  world, 
being  almost  half  the  size  of  the  Earth.  In  diameter 
he  measures  only  6,728  kilometers  (4,172  miles),  and 
his  circumference  is  21,125  kilometers  (13,000  miles). 
His  surface  is  only  y2^  of  the  terrestrial  surface,  and 
his  volume  only  y1^  of  our  own. 

133 


ASTRONOMY  FOR  AMATEURS 

This  difference  in  volume  causes  Mars  to  be  an 
earth  in  miniature.  When  we  study  his  aspects,  his 
geography,  his  meteorology,  we  seem  to  see  in  space  a 
reduction  of  our  own  abode,  with  certain  dissimilarities 
that  excite  our  curiosity,  and  make  him  even  more  inter- 
esting to  us. 

The  Martian  world  weighs  nine  times  and  a  half 
less  than  our  own.  If  we  represent  the  weight  of  the 
Earth  by  1,000,  that  of  Mars  would  be  represented  by 
105.  His  density  is  much  less  than  our  own;  it  is  only 
y7^  that  of  the  Earth.  A  man  weighing  70  kilograms, 
transported  to  the  adjacent  globe,  would  weigh  only 
26  kilograms. 

The  earliest  telescopic  observations  revealed  the 
existence  of  more  or  less  accentuated  markings  upon 
the  surface  of  Mars.  The  progress  of  optics,  admitting 
of  greater  magnifications,  exhibited  the  form  of  these 
patches  more  clearly,  while  the  study  of  their  motions 
enabled  the  astronomers  to  determine  with  remarkable 
precision  the  diurnal  rotation  of  this  planet.  It  occurs 
in  24  hours,  37  minutes,  23.65  seconds.  Day  and  night 
are  accordingly  a  little  longer  on  Mars  than  on  the 
Earth,  but  the  difference  is  obviously  inconsiderable. 
The  year  of  Mars  consists  of  668  Martian  days.  The 
inclination  of  the  axis  of  rotation  of  this  globe  upon 
the  plane  of  its  orbit  is  much  the  same  as  our  own.  In 

134 


THE  PLANETS 

consequence,  its  seasons  are  analogous  to  ours  in  in- 
tensity, while  twice  the  length,  the  Martian  year  be- 
ing almost  equal  to  two  of  our  years.  The  intensity  of 
the  seasons  is  indeed  more  accentuated  than  upon  the 
Earth,  since  the  orbit  of  Mars  is  very  elongated.  But 
there,  as  here,  are  three  quite  distinct  zones:  the  torrid, 
the  temperate,  and  the  glacial. 

By  means  of  the  telescope  we  can  follow  the  varia- 
tions of  the  Martian  seasons,  especially  in  what  concerns 
the  polar  snows,  which  regularly  aggregate  during  the 
winter,  and  melt  no  less  regularly  during  the  heat  of  the 
summer.  These  snows  are  very  easily  observed,  and 
stand  out  clearly  with  dazzling  whiteness.  The  reader 
can  judge  of  them  by  the  accompanying  figure,  which 
sums  up  the  author's  observations  during  one  of  the 
recent  oppositions  of  Mars  (1900-1901).  The  size  of 
the  polar  cap  diminished  from  4,680  kilometers  to  840. 
The  solstice  of  the  Martian  summer  was  on  April  nth. 
The  snows  were  still  melting  on  July  6th.  Sometimes 
they  disappear  almost  entirely  during  the  Martian 
month  that  corresponds  to  our  month  of  August,  as 
never  happens  with  our  polar  ice.  Hence,  though  this 
planet  is  farther  away  from  the  Sun  than  ourselves,  it 
does  not  appear  to  be  colder,  or,  at  any  rate,  it  is  certain 
that  the  polar  snows  are  much  less  thick. 

On  the  other  hand,  there  are  hardly  ever  clouds  on 

135 


ASTRONOMY  FOR  AMATEURS 


October  23,  1900. 


December  22,  1900. 


January  14,  1901. 


February  15,  1901. 


March  22,  1901. 


April  21,  1901. 


May  19,  1901. 


June  14,  1901. 


July  6,  1901. 

FIG.  40. — Dimi- 
nution of  the  polar 
snows  of  Mars 
during  the  sum- 
mer. 


Mars;  the  Martian  atmosphere  is  al- 
most always  limpid,  and  one  can  say 
that  fine  weather  is  the  chronic  state 
of  the  planet.  At  times,  light  fogs  or 
a  little  vapor  will  appear  in  certain 
regions,  but  they  are  soon  dissipated, 
and  the  sky  clears  up  again. 

Since  the  invention  of  the  teles- 
cope, a  considerable  number  of  draw- 
ings have  been  made,  depicting  Mars 
under  every  aspect,  and  the  agree- 
ment between  these  numerous  obser- 
vations gives  us  a  sufficient  acquaint- 
ance with  the  planet  to  admit  of  our 
indicating  the  characteristic  features 
of  its  geography,  and  of  drawing  out 
areographic  maps  (Ares,  Mars).  Its 
appearance  can  be  judged  of  from 
the  two  drawings  here  reproduced,  as 
made  (February,  1901)  at  the  Observ- 
atory of  Juvisy,  and  from  the  general 
chart  drawn  from  the  total  sum  of 
observations  (Figs.  41,  42  and  43). 

It  will  be  seen  at  the  first  glance 
that  the  geography  of  Mars  is  very 
different  from  that  of  our  own  globe: 

136 


THE  PLANETS 


while  three-quarters  of  the  Earth  are  covered  with  the 
liquid  element,  Mars  seems  to  be  more  evenly  divided, 
and  must  indeed  have  rather  more  land  than  water. 
We  find  no  immense  oceans  surrounding  the  continents, 
and  separating  them  like  islands;  on  the  contrary,  the 
seas  are  reduced  to  long  gulfs  compressed  between  the 
shores,  like  the 
Mediterranean 
fcr  example,  nor 
is  it  even  certain 
that  these  gray 
spots  do  all  rep- 
resent true  seas. 
It  has  been 
agreed  to  term 
sea  the  parts  that 
are  lightly  tinged 
with  green,  and 
to  give  the  name 
o  f  continent  t  o 
the  spots  colored  yellow.  That  is  the  hue  of  the  Mar- 
tian soil,  due  either  to  the  soil  itself^  which  would  re- 
semble that  of  the  Sahara,  or,  to  take  a  less  arid  region, 
that  seen  on  the  line  between  Marseilles  and  Nice,  in 
the  vicinity  of  the  Esterels;  or  perhaps  to  some  peculiar 
vegetation.  During  ascents  in  a  balloon,  the  author 

137 


FIG.  41. — Telescopic  aspect  of  the  planet 
Mars  (Feb.,  1901). 


ASTRONOMY  FOR  AMATEURS 


has  often  remarked  that  the  hue  of  the  ripe  corn,  with 
the  Sun  shining  on  it,  is  precisely  that  presented  to  us 
by  the  continents  of  Mars  in  the  best  hours  for  obser- 
vation. 

As  to  the  "seas,"  it  is  pretty  certain  that  there  must 
be  water,  or  some  kind  of  liquid,  deriving  above  all 

from  the  melting 
of  the  polar 
snows  in  spring 
anJ  summer;  but 
it  may  possibly 
be  in  conjunction 
with  some  vege- 
tation, aquatic 
plants,  or  per- 
haps vast  mea- 
dows, which  ap- 
pear to  us  from 
here  to  be  the 
more  consider- 
able in  proportion  as  the  water  that  nourishes  them 
has  been  more  abundant. 

Mars,  like  our  globe,  is  surrounded  with  a  protective 
atmosphere,  which  retains  the  rays  of  the  Sun,  and  must 
'preserve  a  medium  temperature  favorable  to  the  con- 
servation of  life  upon  the  surface  of  the  planet.  But  the 

138 


FIG.  42. — Telescopic  aspect  of  the  planet 
Mars  (Feb.,  1901). 


THE  PLANETS 

circulation  of  the  water,  so  important  to  terrestrial  life, 
whether  animal  or  vegetable,  which  is  effected  upon  our 
planet  by  the  evaporation  of  the  seas,  clouds,  winds, 
rains,  wells,  rivers  and  streams,  comes  about  quite  dif- 
ferently on  Mars;  for,  as  was  remarked  above,  it  is  rarely 
that  any  clouds  are  observed  there.  Instead  of  being 
vertical,  as  here,  this  circulation  is  horizontal:  the 
water  coming  from  the  source  of  the  polar  snows  finds 
its  way  into  the  canals  and  seas,  and  returns  to  be  con- 
densed at  the  poles  by  a  light  drift  of  invisible  vapors 
directed  from  the  equator  to  the  poles.  There  is  never 
any  rain. 

We  have  spoken  of  canals.  One  of  the  great  puzzles 
of  the  Martian  world  is  incontestably  the  appearance 
of  straight  lines  that  furrow  its  surface  in  all  directions, 
and  seem  to  connect  the  seas.  M.  Schiaparelli,  the 
distinguished  Director  of  the  Observatory  of  Milan, 
who  discovered  them  in  1877,  called  them  canals,  with- 
out, however,  postulating  anything  as  to  their  real 
nature.  Are  they  indeed  canals  ?  These  straight  lines, 
measuring  sometimes  600  kilometers  (372  miles)  in 
length,  and  more  than  100  kilometers  (62  miles)  in 
breadth,  have  much  the  same  hue  as  the  seas  on  which 
they  open.  For  a  quarter  of  a  century  they  have  been 
surveyed  by  the  greater  number  of  our  observers.  But 
it  must  be  confessed  that,  even  with  the  best  instruments, 

139 


140 


THE  PLANETS 

we  only  approach  Mars  at  a  distance  of  60,000  kilometers 
(37,200  miles),  which  is  still  a  little  far  off,  and  we  may 
be  sure  that  we  do  not  distinguish  the  true  details  of 
the  surface.*  These  details  at  the  limits  of  visibility 
produce  the  appearance  of  canals  to  our  eyes.  They 
may  possibly  be  lines  of  lakes,  or  oases.  The  future 
will  no  doubt  clear  up  this  mystery  for  us. 

As  to  the  inhabitants  of  Mars,  this  world  is  in  a 
situation  as  favorable  as  our  Earth  for  habitation,  and 
it  would  be  difficult  to  discover  any  reason  for  perpetual 
sterility  there.  It  appears  to  us,  on  the  contrary,  by  its 
rapid  and  frequent  variations  of  aspect,  to  be  a  very 
living  world.  Its  atmosphere,  which  is  always  clear,  has 
not  the  density  of  our  own,  and  resembles  that  of  the 
highest  mountains.  The  conditions  of  existence  there 
vary  from  ours,  and  appear  to  be  more  delicate,  more 
ethereal. 

There  as  here,  day  succeeds  to  night,  spring  softens 
the  rigors  of  winter;  the  seasons  unfold,  less  disparate 
than  our  own,  of  which  we  have  such  frequent  reason 
to  complain.  The  sky  is  perpetually  clear.  There  are 
never  tempests,  hurricanes,  nor  cyclones,  the  wind  never 
gets  up  any  force  there,  on  account  of  the  rarity  of  the 
atmosphere,  and  the  low  intensity  of  weight. 

*  Strictly  speaking,  I  kilometer  =  0.6214  m^e-  Here,  as  throughout, 
the  equivalents  are  only  given  in  round  numbers. — TRANSLATOR. 

141 


ASTRONOMY  FOR  AMATEURS 

Differing  from  ours,  this  world  may  well  be  a  more 
congenial  habitation.  It  is  more  ancient  than  the 
Earth,  smaller,  less  massive.  It  has  run  more  quickly 
through  the  phases  of  its  evolution.  Its  astral  life  is 
more  advanced,  and  its  Humanity  should  be  superior 
to  our  own,  just  as  our  successors  a  million  years  hence, 
for  example,  will  be  less  coarse  and  barbarous  than  we 
are  at  present:  the  law  of  progress  governs  all  the 
worlds,  and,  moreover,  the  physical  constitution  of  the 
planet  Mars  is  less  dense  than  our  own. 

There  is  no  need  to  despair  of  entering  some  day 
into  communication  with  thrse  unknown  beings.  The 
luminous  points  that  have  been  observed  are  no  signals, 
but  high  summits  or  light  clouds  illuminated  by  the 
rising  or  setting  sun.  But  the  idea  of  communication 
with  them  in  the  future  is  no  more  audacious  and  no 
less  scientific  than  the  invention  of  spectral  analysis, 
X-rays,  or  wireless  telegraphy. 

We  may  suppose  that  the  study  of  astronomy  is 
further  advanced  in  Mars  than  on  the  Earth,  because 
humanity  itself  has  advanced  further,  and  because  the 
starry  sky  is  far  finer  there,  far  easier  to  study,  owing 
to  the  limpidity  of  its  pure,  clear  atmosphere. 

Two  small  moons  (hardly  larger  than  the  city  of 
Paris)  revolve  rapidly  round  Mars;  they  are  called 
Phobos  and  Deimos.  The  former,  at  a  distance  of 

142 


THE  PLANETS 

6,000  kilometers  (3,730  miles)  from  the  surface,  accom- 
plishes its  revolution  rapidly,  in  seven  hours,  thirty-nine 
minutes,  and  thus  makes  the  entire  circle  of  the  Heavens 
three  times  a  day.  The  second  gravitates  at  20,000  kilo- 
meters (12,400  miles),  and  turns  round  its  center  of  at- 
traction in  thirty  hours  and  eighteen  minutes.  These 
two  satellites  were  discovered  by  Mr.  Hall,  at  the 
University  of  Washington,  in  the  month  of  August, 


Among  the  finest  and  most  interesting  of  the  celes- 
tial phenomena  admired  by  the  Martians,  at  certain 
epochs  of  the  year,  —  now  at  night  when  the  Sun  has 
plunged  into  his  fiery  bed,  now  in  the  morning,  a  little 
before  the  aurora,  —  is  a  magnificent  star  of  first  magni- 
tude, never  far  removed  from  the  orb  of  day,  which  pre- 
sents to  them  the  same  aspects  as  does  Venus  to  our- 
selves. This  splendid  orb,  which  has  doubtless  received 
the  most  flattering  names  from  those  who  contemplate 
it,  this  radiant  star  of  a  beautiful  greenish  blue,  courses 
in  space  accompanied  by  a  little  satellite,  sparkling  like 
some  splendid  diamond,  after  sunset,  in  the  clear  sky  of 
Mars.  This  superb  orb  is  the  Earth,  and  the  little  star 
accompanying  it  is  the  Moon. 

Yes,  to  the  Martians  our  Earth  is  a  star  of  the  morn- 
ing and  evening;  doubtless  they  have  determined  her 

143 


ASTRONOMY  FOR  AMATEURS 


FIG,  44. — The  Earth  viewed  from  Mars. 

phases.  Many  a  vow,  and  many  a  hope  must  have 
been  wafted  toward  her,  more  than  one  broken  heart 
must  have  permitted  its  unrealized  dreams  to  wander 

144 


THE  PLANETS 

forth  to  our  planet  as  to  an  abode  of  happiness  where 
all  who  have  suffered  in  their  native  world  might  find  a 
haven.  But  our  planet,  alas!  is  not  as  perfect  as  they 
imagine. 

We  must  not  dally  upon  Mars,  but  hasten  our  celes* 
tial  excursion  toward  Jupiter. 


I4J 


CHAPTER  VI 

THE   PLANETS 

B. — JUPITER,  SATURN,  URANUS,  NEPTUNE. 

BEFORE  we  attack  the  giant  world  of  our  system,  we 
must  halt  for  a  few  moments  upon  the  minor  planets 
which  circulate  between  the  orbit  of  Mars  and  that  of 
Jupiter.  These  minute  asters,  little  worlds,  the  largest 
of  which  measures  scarcely  more  than  100  kilometers 
(62  miles)  in  diameter,  are  fragments  of  cosmic  matter 
that  once  belonged  to  a  vast  ring,  formed  at  the  time 
when  the  solar  system  was  only  an  immense  nebula; 
and  which,  instead  of  condensing  into  a  single  globe 
coursing  between  Mars  and  Jupiter,  split  up  into  a  con- 
siderable quantity  of  particles  constituting  at  the  present 
time  the  curious  and  highly  interesting  Republic  of  the 
Asteroids. 

These  lilliputian  worlds  at  first  received  the  names 
of  the  more  celebrated  of  the  minor  mythological  divini- 
ties— Ceres,  Pallas,  Juno,  Vesta,  etc.,  but  as  they  rapidly 
increased  in  number,  it  was  found  necessary  to  call  them 
by  modern,  terrestrial  names,  and  more  than  one  daugh- 

146 


THE  PLANETS 

ier  of  Eve,  the  Egeria  of  some  astronomer,  now  has 
her  name  inscribed  in  the  Heavens.  The  first  minor 
planet  was  discovered  on  the  first  day  of  the  nineteenth 
century,  January  I,  1801,  by  Piazzi,  astronomer  at 
Palermo.  While  he  was  observing  the  small  stars  in 
the  constellation  of  the  Bull  beneath  the  clear  Sicilian 
skies,  this  famous  astronomer  noticed  one  that  he  had 
never  seen  before. 

The  next  night,  directing  his  telescope  to  the  same 
part  of  the  Heavens,  he  perceived  that  the  fair  unknown 
had  moved  her  station,  and  the  observations  of  the  fol- 
lowing days  left  him  no  doubt  as  to  the  nature  of  the 
visitor:  she  was  a  planet,  a  wandering  star  among  the 
constellations,  revolving  round  the  Sunn  This  new- 
comer was  registered  under  the  name  of  Ceres. 

Since  that  epoch  several  hundreds  of  them  have 
been  discovered,  occupying  a  zone  that  extends  over  a 
space  of  more  than  400  million  kilometers  (249,000,000 
miles).  These  celestial  globules  are  invisible  to  the 
naked  eye,  but  no  year  passes  without  new  and  numerous 
recruits  being  added  to  the  already  important  catalogue 
of  these  minute  asters  by  the  patient  observers  of  the 
Heavens.  To-day,  they  are  most  frequently  discovered 
by  the  photographic  method  of  following  the  displace- 
ment of  the  tiny  moving  points  upon  an  exposed  sensi* 
live  plate. 

11  147 


ASTRONOMY  FOR  AMATEURS 


JUPITER 

And  now  let  us  bow  respectfully  before  Jupiter,  the 
giant  of  the  worlds.  This  glorious  planet  is  indeed 
King  of  the  Solar  System. 

While  Mercury  measures  only  4,750  kilometers 
(2,946  miles)  in  diameter,  and  Mars  6,728  (4,172), 
Jupiter  is  no  less  than  140,920  kilometers  (87,400  miles) 
in  breadth;  that  is  to  say,  eleven  times  larger  than  the 
Earth.  He  is  442,500  kilometers  (274,357  miles)  in 
circumference. 

In  volume  he  is  equivalent  to  1,279  terrestrial  globes; 
hence  he  is  only  a  million  times  smaller  than  the  Sun, 
The  previously  described  planets  of  our  system,  Mer- 
cury, Venus,  the  Earth,  and  Mars  combined,  would 
form  only  an  insignificant  mass  in  comparison  with  this 
colossus.  A  hundred  and  twenty-six  Earths  joined 
into  one  group  would  present  a  surface  whose  extent 
would  still  not  be  quite  as  vast  as  the  superficies  of  this 
titanic  world.  This  immense  globe  weighs  310  times 
more  than  that  which  we  inhabit.  Its  density  is  only 
the  quarter  of  our  own;  but  weight  is  twice  and  a  half 
times  as  great  there  as  here.  The  constituents  of  things 
and  beings  are  thus  composed  of  materials  lighter  than 
those  upon  the  Earth;  but,  as  the  planet  exerts  a  force 

148 


THE  PLANETS 

of  attraction  twice  and  a  half  times  as  powerful,  they 
are  in  reality  heavier  and  weigh  more.  A  graceful 
maiden  weighing  fifty  kilograms  would  if  transported 
to  Jupiter  immediately  be  included  in  the  imposing 
society  of  the  "Hundred  Kilos." 

Jupiter  rotates  upon  himself  with  prodigious  rapidity. 
He  accomplishes  his  diurnal  revolution  in  less  than  ten 
hours!  There  the  day  lasts  half  as  long  as  here,  and 
while  we  reckoned  fifteen  days  upon  our  calendar,  the 
Jovian  would  count  thirty-six.  As  Jupiter's  year  equals 
nearly  twelve  of  ours,  the  almanac  of  that  planet  would 
contain  10,455  days!  Obviously,  our  pretty  little  pocket 
calendars  would  never  serve  to  enumerate  all  the  dates 
in  this  vast  world. 

This  splendid  globe  courses  in  space  at  a  distance 
of  775,000,000  kilometers  (480,500,000  miles)  from  the 
Sun.  Hence  it  is  five  times  (5.2)  as  remote  from  the  orb 
of  day  as  our  Earth,  and  its  orbit  is  five  times  vaster  than 
our  own.  At  that  distance  the  Sun  subtends  a  diameter 
five  times  smaller  than  that  which  we  see,  and  its  surface 
is  twenty-seven  times  less  extensive;  accordingly  this 
planetary  abode  receives  on  an  average  twenty-seven 
times  less  light  and  heat  than  we  obtain. 

In  the  telescope  Jupiter  presents  an  aspect  analogous 
to  that  likely  to  be  exhibited  by  a  world  covered  with 
clouds,  and  enveloped  in  dense  vapors  (Fig.  45). 

149 


ASTRONOMY  FOR  AMATEURS 

It  is,  in  fact,  the  seat  of  formidable  perturbations, 
r>f  strange  revolutions  by  which  it  is  perpetually  con- 
vulsed, for  although  of  more  ancient  formation  than 

"  C5 

the  Earth,  this  celestial  giant  has  not  yet  arrived  at  the 
stable   condition   of  our  dwelling-place.      Owing   to   its 


FIG.  45. — Telescopic  aspect  of  Jupiter. 

considerable  volume,  this  globe  has  probably  preserved 
its  original  heat,  revolving  in  space  as  an  obscure  Sun, 
but  perhaps  still  burning.  In  it  we  see  what  our  own 
planet  must  have  been  in  its  primordial  epoch,  in  the 
pristine  times  of  terrestrial  genesis. 

150 


THE  PLANETS 

Since  its  orbital  revolution  occupies  nearly  twelve 
years,  Jupiter  comes  back  into  opposition  with  the  Sun 
every  399  days,  L  e.,  i  year,  34  days,  that  is  with  one 
month  and  four  days'  delay  each  year.  At  these  periods 
it  is  located  at  the  extremity  of  a  straight  line  which, 
passing  by  the  Earth,  is  prolonged  to  the  Sun.  These 
are  the  epochs  to  be  selected  for  observation.  It  shines 
then,  all  night,  like  some  dazzling  star  of  the  first  magni- 
tude, of  excessive  whiteness:  nor  can  it  be  confounded 
either  with  Venus,  more  luminous  still  (for  she  is  never 
visible  at  midnight,  in  the  full  South,  but  is  South-west 
in  the  evening,  or  South-east  in  the  morning),  nor  with 
Mars,  whose  fires  are  ruddy. 

In  the  telescope,  the  immense  planet  presents  a 
superb  disk  that  an  enlargement  of  forty  times  shows  us 
to  be  the  same  size  to  all  appearance  as  that  of  the  Moon 
seen  with  the  unaided  eye.  Its  shape  is  not  absolutely 
spherical,  but  spheroid — that  is,  flattened  at  the  poles. 
The  flattening  is  -pp 

We  know  that  the  Earth's  axis  dips  a  certain  quantity 
on  the  plane  of  her  orbit,  and  that  it  is  this  inclination 
that  produces  the  seasons.  Now  it  is  not  the  same  for 
Jupiter.  His  axis  of  rotation  remains  almost  vertical 
throughout  the  course  of  his  year,  and  results  in  the 
complete  absence  of  climates  and  seasons.  There  is 
neither  glacial  zone,  nor  tropic  zone;  the  position  of 


ASTRONOMY  FOR  AMATEURS 

Jupiter  is  eternally  that  of  the  Earth  at  the  season  of  the 
equinox,  and  the  vast  world  enjoys,  as  it  were,  perpetual 
spring.  It  knows  neither  the  hoar-frost  nor  the  snows 
of  winter.  The  heat  received  from  the  Sun  diminishes 
gradually  from  the  equator  to  the  poles  without  abrupt 
transitions,  and  the  duration  of  day  and  night  is  equal 
there  throughout  the  entire  year,  under  every  latitude. 
A  privileged  world,  indeed! 

It  is  surrounded  by  a  very  dense,  thick  atmosphere, 
which  undergoes  more  extensive  variations  than  could 
be  produced  by  the  Sun  at  such  a  distance.  Spectral 
analysis  detects  a  large  amount  of  water-vapor,  showing 
that  this  planet  still  possesses  a  very  considerable  quan- 
tity of  intrinsic  heat. 

Most  conspicuous  upon  this  globe  are  the  larger  or 
smaller  bands  or  markings  (gray  and  white,  sometimes 
tinted  yellow,  or  of  a  maroon  or  chocolate  hue)  by  which 
its  surface  is  streaked,  particularly  in  the  vicinity  of  the 
equator.  These  different  belts  vary,  and  are  constantly 
modified,  either  in  form  or  color.  Sometimes,  they  are 
irregular,  and  cut  up;  at  others  they  are  interspersed 
with  more  or  less  brilliant  patches.  These  patches  are 
not  affixed  to  the  surface  of  the  globe,  like  the  seas  and 
continents  of  the  Earth;  nor  do  they  circulate  round 
the  planet  like  the  satellites,  in  more  or  less  elongated 
and  regular  revolutions,  but  are  relatively  mobile,  like 

152 


THE  PLANETS 

our  clouds  in  the  atmosphere,  while  observation  of  their 
motion  does  not  give  the  exact  period  of  the  rotation  of 
Jupiter.  Some  only  appear  upon  the  agitated  disk  to 
vanish  very  quickly  ;  others  subsist  for  a  considerable 
period. 

One  has  been  observed  for  over  a  quarter  of  a  cen- 
tury, and  appears  to  be  almost  immobile  upon  this 
colossal  globe.  This  spot,  which  was  red  at  its  first 
appearance,  is  now  pale  and  ghostly.  It  is  oval  (vide 
Fig.  45)  and  measures  42,000  kilometers  (26,040  miles) 
in  length  by  15,000  kilom.  (9,300  m.)  in  width.  Hence 
it  is  about  four  times  as  long  as  the  diameter  of  our 
Earth;  that  is,  relatively  to  the  size  of  Jupiter,  as  are 
the  dimensions  of  Australia  in  proportion  to  our  globe. 
The  discussion  of  a  larger  number  of  observations  leads 
us  to  see  in  it  a  sort  of  continent  in  the  making,  a  scoria 
recently  ejected  from  the  mobile  and  still  liquid  and 
heated  surface  of  the  giant  Jupiter.  The  patch,  however, 
oscillates  perceptibly,  and  appears  to  be  a  floating  island. 

We  must  add  that  this  vast  world,  like  the  Sun,  does 
not  rotate  all  in  one  period.  Eight  different  currents  can 
be  perceived  upon  its  surface.  The  most  rapid  is  that 
of  the  equatorial  zone,  which  accomplishes  its  revolu- 
tion in  9  hours,  50  minutes,  29  seconds.  A  point  situated 
on  the  equator  is  therefore  carried  forward  at  a  speed  of 
12,500  meters  (7  miles)  per  second,  and  it  is  this  giddy 


ASTRONOMY  FOR  AMATEURS 

velocity  of  Jupiter  that  has  produced  the  flattening  of 
the  poles.  From  the  equator  to  the  poles,  the  swiftness 
of  the  currents  diminishes  irregularly,  and  the  difference 
amounts  to  about  five  minutes  between  the  movement 
of  the  equatorial  stream,  and  that  of  the  northern  and 
southern  currents.  But  what  is  more  curious  still  is 
that  the  velocity  of  one  and  the  same  stream  is  subject 
to  certain  fluctuations;  thus,  in  the  last  quarter  of  a 
century,  the  speed  of  the  equatorial  current  has  pro- 
gressively diminished.  In  1879,  the  velocity  was  9  hours, 
49  minutes,  59  seconds,  and  now  it  is,  as  we  have  already 
seen,  9  hours,  50  minutes,  29  seconds,  which  represents 
a  substantial  reduction.  The  rotation  of  the  red  patch^ 
at  25  degrees  of  the  southern  latitude,  is  effected  in 
9  hours,  55  minutes,  40  seconds. 

We  are  confronted  with  a  strange  and  mysterious 
world.  It  is  the  world  of  the  future. 

This  giant  gravitates  in  space  accompanied  by  a 
suite  of  five  satellites.  These  are: 

Names.                   Distance  from  surface  of  Jupiter.        Time  of  revolution. 
Kilometers.  Miles.  Days.  Hours. 

5 200,000  124,000  H 

1.  lo 430,000  266,000  i  18 

2.  Europa 682,000  422,840  3  13 

3.  Ganymede 1,088,000  674,560  7  4 

4.  Callisto 1,914,000  1,186,680  16  16 

The  four  principal  satellites  of  Jupiter  were  dis- 
covered at  the  same  time,  on  the  same  evenings  (Jan- 

154 


THE  PLANETS 

uary  7  and  8,  1610),  by  the  two  astronomers  who  were 
pointing  their  telescopes  at  Jupiter:  Galileo  in  Itatyj 
and  Simon  Marius  in  Germany. 

On  September  9,  1892,  Mr.  Barnard,  astronomer  of 
the  Lick  Observatory,  California,  discovered  a  new 
satellite,  extremely  minute,  and  very  near  the  enormous 
planet.  It  has  so  far  received  no  name,  and  is  known 
as  the  fifth,  although  the  four  principal  are  numbered 
in  the  order  of  their  distances. 


FIG.  46. — Jupiter  and  his  four  principal  satellites. 

The  four  classical  satellites  are  visible  in  the  smallest 
instruments  (Fig.  46):  the  third  is  the  most  volumi- 
nous. 

Such  is  the  splendid  system  of  the  mighty  Jupiter. 
Once,  doubtless,  this  fine  planet  illuminated  the  troop  of 
worlds  that  derived  their  treasure  of  vitality  from  him 
with  his  intrinsic  light:  to-day,  however,  these  moons 
in  their  turn  shed  upon  the  extinct  central  globe  the 
pale  soft  light  which  they  receive  from  our  solar  focus, 

155 


ASTRONOMY  FOR  AMATEURS 

illuminating  the  brief  Jovian  nights  (which  last  less  than 
five  hours,  on  account  of  the  twilight)  with  their  variable 
brilliancy. 

At  the  distance  of  the  first  satellite,  Jupiter  exhibits 
a  disk  fourteen  hundred  times  vaster  than  that  of  the  Full 
Moon!  What  a  dazzling  spectacle,  what  a  fairy  scene 
must  the  enormous  star  afford  to  the  inhabitants  of  that 
tiny  world!  And  what  a  shabby  figure  must  our  Earth 
and  Moon  present  in  the  face  of  such  a  body,  a  real 
miniature  of  the  great  solar  system! 

Our  ancestors  were  well  inspired  when  they  attribu- 
ted the  sovereignty  of  Olympus  to  this  majestic  planet. 
His  brilliancy  corresponds  with  his  real  grandeur.  His 
dominion  in  the  midnight  Heavens  is  unique.  Here 
again,  as  for  Venus,  Mars,  and  Mercury,  astronomy  has 
created  the  legend  of  the  fables  of  mythology. 

Let  us  repeat  in  conclusion  that  our  Earth  becomes 
practically  invisible  for  the  inhabitants  of  the  other 
worlds  beyond  the  distance  of  Jupiter. 

SATURN 

Turn  back  now  for  a  moment  to  the  plan  of  the 
Solar  System. 

We  had  to  cross  775 "million  kilometers  (480,000,000 
miles)  when  we  left  the  Sun,  in  order  to  reach  the  im- 

156 


THE  PLANETS 

mense  orb  of  Jupiter,  which  courses  in  space  at  626 
million  kilometers  (388,000,000  miles)  from  the  terres- 
trial orbit.  From  Jupiter  we  had  to  traverse  a  distance 
of  646  million  kilometers  (400,000,000  miles)  in  order  to 
reach  the  marvelous  system  of  Saturn,  where  our  eyes 
and  thoughts  must  next  alight. 

Son  of  Uranus  and  Vesta,  Saturn  was  the  God  of 
Time  and  Fate.  He  is  generally  represented  as  an  aged 
man  bearing  a  scythe.  His  mythological  character  is 
only  the  expression  of  his  celestial  aspect,  as  we  have 
seen  for  the  brilliant  Jupiter,  for  the  pale  Venus,  the 
ruddy  Mars,  and  the  agile  Mercury.  The  revolution 
of  Saturn  is  the  slowest  of  any  among  the  planets  known 
to  the  ancients.  It  takes  almost  thirty  years  for  its 
accomplishment,  and  at  that  distance  the  Saturnian 
world,  though  it  still  shines  with  the  brilliancy  of  a  star 
of  the  first  magnitude,  exhibits  to  our  eyes  a  pale  and 
leaden  hue.  Here  is,  indeed,  the  god  of  Time,  with 
slow  and  almost  funereal  gait. 

Poor  Saturn  won  no  favor  with  the  poets  and  astrol- 
ogers. He  bore  the  horrid  reputation  of  being  the 
inexhaustible  source  of  misfortune  and  evil  fates, — 
whereof  he  is  wholly  innocent,  troubling  himself  not  at 
all  with  our  world  nor  its  inhabitants. 

This  world  travels  in  the  vastness  of  the  Heavens  at 
a  distance  of  1,421  million  kilometers  (881,000,000  miles) 


ASTRONOMY  FOR  AMATEURS 

from  the  Sun.  Hence  it  is  ten  times  farther  from  the  orb 
of  day  than  the  Earth,  though  still  illuminated  and  gov- 
erned by  the  Sun-God.  Its  gigantic  orbit  is  ten  times 
larger  than  our  own. 

Its  revolution  round  the  Sun  is  accomplished  in 
10,759  days,  /.  e.9  29  years,  167  days,  and  as  this  strange 
planet  rotates  upon  itself  with  great  rapidity  in  10  hours, 
15  minutes,  its  year  comprises  no  less  than  25,217  days. 
What  a  calendar!  The  Saturnians  must  needs  have  a 
prodigious  memory  not  to  get  hopelessly  involved  in  this 
interminable  number  of  days.  A  curious  world,  where 
each  year  stands  for  almost  thirty  of  our  own,  and  where 
the  day  is  more  than  half  as  short  again  as  ours.  But 
we  shall  presently  find  other  and  more  extraordinary 
differences  on  this  planet. 

In  the  first  place  it  is  nearly  nine  and  a  half  times 
larger  than  our  world.  It  is  a  globe,  not  spherical,  but 
spheroidal,  and  the  flattening  of  its  poles,  which  is  one- 
tenth,  exceeds  that  of  all  the  other  planets,  even  Jupiter. 
It  follows  that  its  equatorial  diameter  is  112,500  kilo- 
meters (69,750  miles),  while  its  polar  diameter  measures 
only  110,000  (68,200). 

In  volume,  Saturn  is  719  times  larger  than  the  Earth, 
but  its  density  is  only  yV2o%  °f  °ur  own;  /.  e.,  the  mate- 
rials of  which  it  is  composed  are  much  less  heavy,  so 
that  it  weighs  only  92  times  more  than  our  Earth.  Its 

158 


THE  PLANETS 

surface  is  85  times  vaster  than  that  of  the  Earth,  no 
insignificant  proportion. 

The  dipping  of  Saturn's  axis  of  rotation  is  much  the 
same  as  our  own.  Hence  we  conclude  that  the  sea- 
sons of  this  planet  are  analogous  to  ours  in  relative 
intensity.  Only  upon  this  far-off  world  each  season 
lasts  for  seven  years.  At  the  distance  at  which  it  gravi- 


FIG.  47. — Saturn. 

tates  in  space,  the  heat  and  light  which  it  receives  from 
the  Sun  are  90  times  less  active  than  such  as  reach  our 
selves;  but  it  apparently  possesses  an  atmosphere  ol 
great  density,  which  may  be  constituted  so  that  the  heat 
is  preserved,  and  the  planet  maintained  in  a  calorific 
condition  but  little  inferior  to  our  own. 

In  the  telescope,  the  disk  of  Saturn  exhibits  large 
belts  that  recall  those  of  Jupiter,  though  they  are  broader 

159 


ASTRONOMY  FOR  AMATEURS 

and  less  accentuated  (Fig.  47).  There  are  doubtless 
zones  of  clouds  or  rapid  currents  circulating  in  the  atmos- 
phere. Spots  are  also  visible  whose  displacement  assists 
in  calculating  the  diurnal  motions  of  this  globe. 

The  most  extraordinary  characteristic  of  this  strange 
world  is,  however,  the  existence  of  a  vast  ring,  which  is 
almost  flat  and  very  large,  and  entirely  envelops  the  body 
of  the  planet.  It  is  suspended  in  the  Saturnian  sky, 
like  a  gigantic  triumphal  arch,  at  a  height  of  some 
20,000  kilometers  (12,400  miles)  above  the  equator. 
This  splendid  arch  is  circular,  like  an  immense  crown 
illuminated  by  the  Sun.  From  here  we  only  see  it 
obliquely,  and  it  appears  to  us  elliptical;  a  part  of  the 
ring  seems  to  pass  in  front  of  Saturn,  and  its  shadow 
is  visible  on  the  planet,  while  the  opposite  part  passes 
behind. 

This  ring,  which  measures  284,000  kilometers 
(176,080  miles)  in  diameter,  and  less  than  100  kilometers 
(62  miles)  in  breadth,  is  divided  into  three  distinct  zones: 
the  exterior  is  less  luminous  than  the  center,  which  is 
always  brighter  than  the  planet  itself;  the  interior  is 
very  dark,  and  spreads  out  like  a  dusky  and  faintly 
transparent  veil,  through  which  Saturn  can  be  distin- 
guished. 

What  is  the  nature  of  these  vast  concentric  circles 
that  surround  the  planet  with  a  luminous  halo  ?  They 

1 60 


THE  PLANETS 

are  composed  of  an  innumerable  number  of  particles, 
of  a  quantity  of  cosmic  fragments,  which  are  swept  off 
in  a  rapid  revolution,  and  gravitate  round  the  planet 
at  variable  speed  and  distance.  The  nearer  particles 
must  accomplish  their  revolution  in  5  hours,  50  minutes, 
and  the  most  distant  in  about  12  hours,  5  minutes,  to 


FIG.  48. — Varying  perspective  of  Saturn's  Rings,  as  seen 
from  the  Earth. 

prevent  them  from  being  merged  in  the  surface  of  Saturn ; 
their  own  centrifugal  force  sustains  them  in  space. 

With  a  good  glass  the  effect  of  these  rings  is  most 
striking,  and  one  can  not  refrain  from  emotion  on  con- 
templating this  marvel,  whereby  one  of  the  brothers  of 
our  terrestrial  country  is  crowned  with  a  golden  diadem. 

161 


ASTRONOMY  FOR  AMATEURS 

Its  aspects  vary  with  its  perspective  relative  to  the  Earth^ 
as  may  be  seen  from  the  subjoined  figure  (Fig.  48). 

We  must  not  quit  the  Saturnian  province  without 
mentioning  the  eight  satellites  that  form  his  splendid 
suite: 

Names.                 Distance  from  the  planet.  Time  of  revolution. 

Kilometers.  Miles.  Days.  Hours.  Minutes. 

I.   Mimas 207,000  128,340  22           37 

a.  Enceladus 257,600  159,712  I  8           53 

3.  Tethys 328,800  203,856  I  21            18 

4.  Dione 421,200  261,144  a  J7           4' 

5.  Rhea 588,400  364,808  4  12            25 

6.  Titan 1,364,000  845,680  15  22           41 

7.  Hyperion 1,650,000  1,023,000  21  6            39 

*•  Japhet 3,964,000  2,457,680  79  7            54 

Here  is  a  marvelous  system,  with,  what  is  more,  eight 
different  kinds  of  months  for  the  inhabitants  of  Saturn; 
eight  moons  with  constantly  varying  phases  juggling 
above  the  rings! 

Now  we  shall  cross  at  a  bound  the  1,400  million 
kilometers  (868,000,000  miles)  that  separate  us  from 
the  last  station  but  one  of  the  immense  solar  system. 


URANUS 

On  March  13,  1781,  William  Herschel,  a  Hanoverian 
astronomer  who  had  emigrated  to  England,  having 
abandoned  the  study  of  music  to  devote  himself  to  the 
sublime  science  of  the  Heavens,  was  observing  the  vast 

162 


THE  PLANETS 

fields  with  their  constellations  of  golden  stars,  when  he 
perceived  a  luminous  point  that  appeared  to  him  to 
exceed  that  of  the  other  celestial  luminaries  in  diameter. 
He  replaced  the  magnification  of  his  telescope  by  more 
powerful  eye-pieces,  and  found  that  the  apparent  di- 
ameter of  the  orb  increased  proportionately  with  the 
amplification  of  the  power,  which  does  not  happen  in 
the  case  of  stars  at  infinite  distance.  His  observations 
on  the  following  evenings  enabled  him  to  note  the  slow 
and  imperceptible  movement  of  this  star  upon  the 
celestial  sphere,  and  left  him  in  no  further  doubt: 
there  was  no  star,  but  some  much  nearer  orb,  in  all 
probability  a  comet,  for  the  great  astronomer  dared  not 
predict  the  discovery  of  a  new  planet.  And  it  was  thus, 
under  the  name  of  cometary  orb,  that  the  seventh  child 
of  the  Sun  was  announced.  The  astronomers  sought 
to  determine  the  motions  of  the  new  arrival,  to  dis- 
cover for  it  an  elliptical  orbit  such  as  most  comets  have. 
But  their  efforts  were  vain,  and  after  several  months' 
study  the  conclusion  was  reached  that  here  was  a  new 
planet,  throwing  back  the  limits  of  the  solar  system  to 
a  point  far  beyond  that  of  the  Saturnian  frontier,  as 
admitted  from  antiquity. 

This  new  world  received  the  name  of  Uranus,  father 
of  Saturn,  his  nearest  neighbor  in  the  solar  empire. 
Uranus   shines   in   the   firmament  as   a    small   star   of 
12  163 


ASTRONOMY  FOR  AMATEURS 

sixth  magnitude,  invisible  to  the  unaided  eye  for  normal 
sight,  at  a  distance  of  2,831,000,000  kilometers  (1,755,- 
000,000  miles)  from  the  Sun.  Smaller  than  Jupiter  and 
Saturn,  this  planet  is  yet  larger  than  Mercury,  Venus, 
Mars,  and  the  Earth  together,  thus  presenting  pro- 
portions that  claim  our  respect  and  admiration. 

His  diameter  may  be  taken  at  about  55,000  kilometers 
(34,200  miles),  that  is,  rather  more  than  four  times  the 
breadth  of  the  terrestrial  diameter.  Sixty-nine  times 
more  voluminous  than  the  Earth,  and  seventeen  times 
more  extensive  in  surface,  this  new  world  is  much  less 
than  our  own  in  density.  The  matter  of  which  it  is 
composed  is  nearly  five  times  lighter  than  that  of  our 
globe. 

Spectral  analysis  shows  that  this  distant  planet  is 
surrounded  with  an  atmosphere  very  different  from 
that  which  we  breathe,  enclosing  gases  that  do  not  exist 
in  ours. 

The  Uranian  globe  courses  over  the  fields  of  infinity 
in  a  vast  orbit  seventeen  times  larger  than  our  own,  and 
its  revolution  lasts  36,688  days,  i.  e.,  84  years,  8  days. 
It  travels  slowly  and  sadly  under  the  pale  and  languishing 
rays  of  the  Sun,  which  sends  it  nearly  three  hundred 
times  less  of  light  and  heat  than  we  receive.  At  this 
distance  the  solar  disk  would  present  a  diameter  seven- 
teen times  smaller  than  that  which  we  admire,  and  a 

164 


THE  PLANETS 

surface  three  hundred  times  less  vast.  A  dull  world 
indeed!  And  what  an  interminable  year!  The  idle 
people  who  are  in  the  habit  of  being  bored  must  find 
time  even  longer  upon  Uranus  than  upon  our  little 
Earth,  where  the  days  pass  so  rapidly.  And  if  matters 
are  arranged  there  as  here,  a  babe  of  a  year  old,  begin- 
ning to  babble  in  its  nurse's  arms,  would  already  have 
lived  as  long  as  an  old  man  of  eighty-four  in  this  world. 
But  what  most  seriously  complicates  the  Calendar 
of  the  Uranians  is  the  fact  that  the  four  moons  which 
accompany  the  planet  accomplish  their  revolution  in 
four  different  kinds  of  months,  in  two,  four,  eight,  and 
thirteen  days,  as  is  shown  in  the  following  table: 

Distance  from  the  planet.  Time  of  revolution. 

Kilometers.  Miles.  Days.     Hours.     Minutes. 

1.  Ariel 196,000          121,520         2  12  29 

2.  Umbriel 276,000          171,120         4  3  27 

3.  Titania 450,000         279,000        8  16  56 

4.  Oberon 600,000          372,000       13  n  7 

The  most  curious  fact  is  that  these  satellites  do  not 
rotate  like  those  of  the  other  planets.  While  the  moons 
of  the  Earth,  Mars,  Jupiter,  and  Saturn  accomplish 
their  revolution  from  east  to  west,  the  satellites  of 
Uranus  rotate  in  a  plane  almost  perpendicular  to  the 
ecliptic,  and  it  is  doubtless  the  same  for  the  rotation 
of  the  planet. 

If  we  had  to  quit  the  Earth,  and  fixate  ourselves  upon 


ASTRONOMY  FOR  AMATEURS 

another  world,  we  should  prefer  Mars  to  Uranus,  where 
everything  must  be  so  different  from  terrestrial  arrange- 
ments ?  But  who  knows  ?  Perhaps,  after  all,  this  planet 
might  afford  us  some  agreeable  surprises.  //  ne  faut 
jurer  de  rien. 

NEPTUNE 

And  here  we  reach  the  frontier  of  the  Solar  System, 
as  actually  known  to  us.  In  landing  on  the  world  of 
Neptune,  which  circles  through  the  Heavens  in  eternal 
twilight  at  a  distance  of  more  than  four  milliard  kilo- 
meters (2,480,000,000  miles)  from  the  common  center 
of  attraction  of  the  planetary  orbs,  we  once  again  admire 
the  prodigies  of  science. 

Uranus  was  discovered  with  the  telescope,  Neptune 
by  calculation.  In  addition  to  the  solar  influence,  the 
worlds  exert  a  mutual  attraction  upon  each  other  that 
slightly  deranges  the  harmony  ordered  by  the  Sun.  The 
stronger  act  upon  the  weaker,  and  the  colossal  Jupiter 
alone  causes  many  of  the  perturbations  in  our  great 
solar  family.  Now  during  regular  observations  of  the 
position  of  Uranus  in  space,  some  inexplicable  irregu- 
larities were  soon  perceived.  The  astronomers  having 
full  faith  in  the  universality  of  the  law  of  attraction, 
could  not  do  otherwise  than  attribute  these  irregularities 

166 


THE  PLANETS 

to  the  influence  of  some  unknown  planet  situated  even 
farther  off".     But  at  what  distance  ? 

A  very  simple  proportion,  known  as  Bode's  law, 
has  been  observed,  which  indicates  approximately  the 
relative  distances  of  the  planets  from  the  Sun.  It  is 
as  follows:  Starting  from  o,  write  the  number  3,  and 
double  successively, 

o    3     6     12     24    48     96     192    384. 

Then,  add  the  number  4  to  each  of  the  preceding 
figures,  which  gives  the  following  series: 

4     7     10     16     28     52     100     196     388. 

Now  it  is  a  very  curious  fact  that  if  the  distance 
between  the  Earth  and  the  Sun  be  represented  by  10, 
the  figure  4  represents  the  orbit  of  Mercury,  7  that  of 
Venus,  1 6  of  Mars;  the  figure  28  stands  for  the  medium 
distance  of  the  minor  planets;  the  distances  of  Jupiter, 
Saturn,  and  Uranus  agree  with  52,  100,  and  196. 

The  immortal  French  mathematician  Le  Verrier, 
who  pursued  the  solution  of  the  Uranian  problem,  sup- 
posed naturally  that  the  disturbing  planet  must  be  at 
the  distance  of  388,  and  made  his  calculations  accord- 
ingly. Its  direction  in  the  Heavens  was  indicated  by 
the  form  of  the  disturbances;  the  orbit  of  Uranus  bulg- 
ing, as  it  were,  on  the  side  of  the  disturbing  factor. 

On  August  31,  1846,  Le  Verrier  announced  the 
position  of  the  ultra-Uranian  planet,  and  on  September 

167 


ASTRONOMY  FOR  AMATEURS 

23d  following,  a  German  astronomer,  Galle,  at  the 
Observatory  of  Berlin,  who  had  just  received  this  in- 
telligence, pointed  his  telescope  toward  the  quarter  of 
the  Heavens  designated,  and,  in  fact,  attested  the  pres- 
ence of  the  new  orb.  Without  quitting  his  study  table, 
Le  Verrier,  by  the  sole  use  of  mathematics,  had  de- 
tected, and,  as  it  were,  touched  at  pen's  point  the  mys- 
terious stranger. 

Only,  it  is  proved  by  observation  and  calculation 
that  it  is  less  remote  than  was  expected  from  the  pre- 
ceding law,  for  it  gravitates  at  a  distance  of  300,  given 
that  from  the  Earth  to  the  Sun  as  10. 

This  planet  was  called  Neptune,  god  of  the  seas, 
son  of  Saturn,  brother  of  Jupiter.  The  name  is  well 
chosen,  since  the  King  of  the  Ocean  lives  in  darkness  in 
the  depths  of  the  sea,  and  Le  Verrier's  orb  is  also  plunged 
in  the  semi-obscurity  of  the  depths  of  the  celestial  ele- 
ment. But  it  was  primarily  selected  to  do  justice  to  an 
English  astronomer,  Adams,  who  had  simultaneously 
made  the  same  calculations  as  Le  Verrier,  and  obtained 
the  same  results — without  publishing  them.  His  work 
remained  in  the  records  of  the  Greenwich  Observ- 
atory. 

The  English  command  the  seas,  and  wherever  they 
dip  their  finger  into  the  water  and  find  it  salt,  they  feel 
themselves  "at  home,"  and  know  that  "Neptune's  tri- 

168 


THE  PLANETS 

dent  is  the  scepter  of  the  world,"  hence  this  compli- 
mentary nomenclature. 

Neptune  is  separated  by  a  distance  of  four  mil- 
liards, four  hundred  million  kilometers  from  the  solar 
center. 

At  such  a  distance,  thirty  times  greater  than  that 
which  exists  between  the  Sun  and  our  world,  Neptune 
receives  nine  hundred  times  less  light  and  heat  than 
ourselves;  i.  e.,  Spitzbergen  and  the  polar  regions  of  our 
globe  are  furnaces  compared  with  what  must  be  the 
Neptunian  temperature.  Absolutely  invisible  to  the 
unaided  eye,  this  world  presents  in  the  telescope  the 
aspect  of  a  star  of  the  eighth  magnitude.  With  powerful 
magnifications  it  is  possible  to  measure  its  disk,  which 
appears  to  be  slightly  tinged  with  blue.  Its  diameter  is 
four  times  larger  than  our  own,  and  measures  about 
48,000  kilometers  (29,900  miles),  its  surface  is  sixteen 
times  vaster  than  that  of  the  Earth,  and  to  attain  its 
volume  we  should  have  to  put  together  fifty-five  globes 
similar  to  our  own.  Weight  at  its  surface  must  be  about 
the  same  as  here,  but  its  medium  density  is  only  J  that 
of  the  Earth. 

It  gravitates  slowly,  dragging  itself  along  an  orbit 
thirty  times  vaster  than  that  of  our  globe,  and  its  revolu- 
tion takes  164  years,  281  days,  /.  <?.,  164  years,  9  months. 
A  single  year  of  Neptune  thus  covers  several  generations 

169 


ASTRONOMY  FOR  AMATEURS 

of  terrestrial  life.  Existence  must,  indeed,  be  strange 
in  that  tortoise-footed  world! 

While  in  their  rotation  period,  Mercury  accom- 
plishes 47  kilometers  (29!  miles)  per  second,  and  the 
Earth  29 J  (i8J  miles),  Neptune  rolls  along  his  immense 
orbit  at  a  rate  of  only  5^  kilometers  (about  3^  miles) 
per  second. 

The  vast  distance  that  separates  us  prevents  our 
distinguishing  any  details  of  his  surface,  but  spectral 
analysis  reveals  the  presence  of  an  absorbent  atmos- 
phere in  which  are  gases  unknown  to  the  air  of  our 
planet,  and  of  which  the  chemical  composition  resem- 
bles that  of  the  atmosphere  of  Uranus. 

One  satellite  has  been  discovered  for  Neptune.  It 
has  a  considerable  inclination,  and  rotates  from  east  to 
west. 

And  here  we  have  reached  the  goal  of  our  inter- 
planetary journey.  After  visiting  the  vast  provinces 
of  the  solar  republic,  we  feel  yet  greater  admiration  and 
gratitude  toward  the  luminary  that  governs,  warms, 
and  illuminates  the  worlds  of  his  system. 

In  conclusion,  let  us  again  insist  that  the  Earth, — 
a  splendid  orb  as  viewed  from  Mercury,  Venus,  and 
Mars, — begins  to  disappear  from  Jupiter,  where  she 
becomes  no  more  than  a  tiny  spark  oscillating  from 

170 


THE  PLANETS 

side  to  side  of  the  Sun,  and  occasionally  passing  in  front 
of  him  as  a  small  black  dot.  From  Saturn  the  visibility 
of  our  planet  is  even  more  reduced.  As  to  Uranus  and 
Neptune,  we  are  invisible  there,  at  least  to  eyes  con- 
structed like  our  own.  We  do  not  possess  in  the  Universe 
the  importance  with  which  we  would  endow  ourselves. 
Neptune  up  to  the  present  guards  the  portals  of  our 
celestial  system;  we  will  leave  him  to  watch  over  the 
distant  frontier;  but  before  returning  to  the  Earth,  we 
must  glance  at  certain  eccentric  orbs,  at  the  mad,  capri- 
cious comets,  which  imprint  their  airy  flight  upon  the 
realms  of  space. 


171 


CHAPTER  VII 

THE  COMETS 

SHOOTING  STARS,   BOLIDES,   URANOLITHS  OR  METEORIC  STONES 

WHAT  marvels  have  been  reviewed  by  our  dazzled 
eyes  since  the  outset  of  these  discussions!  We  first 
surveyed  the  magnificent  host  of  stars  that  people  the 
vast  firmament  of  Heaven;  next  we  admired  and  won- 
dered at  suns  very  differently  constituted  from  our  own; 
then  returning  from  the  depths  of  space,  crossing  at  a 
bound  the  abyss  that  separates  us  from  these  mys- 
terious luminaries,  the  distant  torches  of  our  somber 
night,  terrible  suns  of  infinity,  we  landed  on  our  own 
beloved  orb,  the  superb  and  brilliant  day-star.  Thence 
we  visited  his  celestial  family,  his  system,  in  which  our 
Earth  is  a  floating  island.  But  the  journey  would  be 
incomplete  if  we  omitted  certain  more  or  less  vagabond 
orbs,  that  occasionally  approach  the  Sun  and  Earth, 
some  of  which  may  even  collide  with  us  upon  their  celes- 
tial path.  These  are  in  the  first  place  the  comets,  then 
the  shooting  stars,  the  fire-balls,  and  meteorites. 

Glittering,  swift-footed  heralds  of  Immensity,  these 
172 


THE  COMETS 

comets  with  golden  wings  glide  lightly  through  Space, 
shedding  a  momentary  illumination  by  their  presence. 
Whence  come  they  ?  Whither  are  they  bound  ? 

What  problems  they  propound  to  us,  when,  as  in 
some  beautiful  display  of  pyrotechnics,  the  arch  of 
Heaven  is  illuminated  with  their  fantastic  light! 

But  first  of  all — what  is  a  Comet  ? 

If  instead  of  living  in  these  days  of  the  telescope,  of 
spectrum  analysis,  and  of  astral  photography,  we  were 
anterior  to  Galileo,  and  to  the  liberation  of  the  human 
spirit  by  Astronomy,  we  should  reply  that  the  comet  is 
an  object  of  terror,  a  dangerous  menace  that  appears 
to  mortals  in  the  purity  of  the  immaculate  Heavens,  to 
announce  the  most  fatal  misfortunes  to  the  inhabitants 
of  our  planet.  Is  a  comet  visible  in  the  Heavens  ?  The 
reigning  prince  may  make  his  testament  and  prepare  to 
die.  Another  apparition  in  the  firmament  bodes  war, 
famine,  the  advent  of  grievous  pestilence.  The  astrol- 
ogers had  an  open  field,  and  their  fertile  imagination 
might  hazard  every  possible  conjecture,  seeing  that 
misfortunes,  great  or  small,  are  not  altogether  rare  in 
this  sublunar  world. 

How  many  intellects,  and  those  not  the  most  vulgar, 
from  antiquity  to  the  middle  of  the  last  century  cursed 
the  apparition  of  these  hirsute  stars,  which  brought 
desolation  to  the  heart  of  man,  and  poured  their  fatal 

173 


ASTRONOMY  FOR  AMATEURS 

effluvia  upon  the  head  of  poor  Humanity.  The  history 
of  the  superstitions  and  fears  that  they  inspired  of  old 
would  furnish  matter  for  the  most  thrilling  of  romances. 
But,  on  the  other  hand,  the  volume  would  be  little  flat- 
tering to  the  common-sense  of  our  ancestors.  Despite 
the  respect  we  owe  our  forefathers,  let  us  recall  for  a 


FIG.  49. — The  Great  Comet  of  1858. 

moment  the  prejudices  attaching  to  the  most  famous 
comets  whose  passage,  as  observed  from  the  Earth,  has 
been  preserved  to  us  in  history. 

Without  going  back  to  the  Deluge,  we  note  that  the 
Romans  established  a  relation  between  the  Great  Comet 

'74 


THE  COMETS 

of  43  B.  C.  and  the  death  of  Caesar,  who  had  been  assas- 
sinated a  few  months  previously.  It  was,  they  asserted, 
the  soul  of  their  great  Captain,  transported  to  Heaven 
to  reign  in  the  empyrean  after  ruling  here  below.  Were 
not  the  Emperors  Lords  of  both  Earth  and  Heaven  ? 

We  must  in  justice  recognize  that  certain  more  in- 
dependent spirits  emancipated  themselves  from  these 
superstitions,  and  we  may  cite  the  reply  of  Vespasian  to 
his  friends,  who  were  alarmed  at  the  evil  presage  of  a 
flaming  comet:  "Fear  nothing,"  he  said,  "this  bearded 
star  concerns  me  not;  rather  should  it  threaten  my 
neighbor  the  King  of  the  Parthians,  since  he  is  hairy 
and  I  am  bald." 

In  the  year  837  one  of  these  mysterious  visitants 
appeared  in  the  Heavens.  It  was  in  the  reign  of  Lewis 
the  Debonair.  Directly  the  King  perceived  the  comet, 
he  sent  for  an  astrologer,  and  asked  what  he  was  to  con- 
clude from  the  apparition.  As  the  answers  were  un- 
satisfactory he  tried  to  avert  the  augury  by  prayers  to 
Heaven,  by  ordaining  a  general  fast  to  all  his  Court,  and 
by  building  churches.  Notwithstanding,  he  died  three 
years  later,  and  the  historians  profited  by  this  slender 
coincidence  to  set  up  a  correlation  between  the  fatal  star 
and  the  death  of  the  Sovereign.  This  comet,  famous 
in  history,  is  no  other  than  that  of  Halley,  in  one  of  its 
appearances. 

175 


ASTRONOMY  FOR  AMATEURS 

This  comet  returned  to  explore  the  realms  near  the 
Sun  in  1066,  at  the  moment  when  William  of  Normandy 
was  undertaking  the  Conquest  of  England,  and  was  mis- 
guided enough  to  go  across  and  reign  in  London,  instead 
of  staying  at  home  and  annexing  England,  thus  by  his 
action  founding  the  everlasting  rivalry  between  France 
and  this  island.  A  beneficial  influence  was  attributed 
to  the  comet  in  the  Battle  of  Hastings. 

A  few  centuries  later  it  again  came  into  sight  from 
the  Earth,  in  1456,  three  years  after  the  capture  of  Con- 
stantinople by  the  Turks.  Feeling  ran  high  in  Europe, 
and  this  celestial  omen  was  taken  for  a  proof  of  the  an- 
ger of  the  Almighty.  The  moment  was  decisive;  the 
Christians  had  to  be  rescued  from  a  struggle  in  which 
they  were  being  worsted.  At  this  conjuncture,  Pope 
Calixtus  resuscitated  a  prayer  that  had  fallen  into  disuse, 
the  Angelus\  and  ordered  that  the  bells  of  the  churches 
should  be  rung  each  day  at  noon,  that  the  Faithful  might 
join  at  the  same  hour  in  prayer  against  the  Turks  and 
the  Comet.  This  custom  has  lasted  down  to  our  own 
day. 

Again,  to  the  comet  of  1500  was  attributed  the  tem- 
pest that  caused  the  death  of  Bartholomew  Diaz,  a 
celebrated  Portuguese  navigator,  who  discovered  the 
Cape  of  Good  Hope. 

In  1528  a  bearded  star  of  terrific  aspect  alarmed  the 

176 


THE  COMETS 

world,  and  the  more  serious  spirits  were  influenced  by 
this  menacing  comet,  which  burned  in  the  Heavens  like 
"a  great  and  gory  sword."  In  a  chapter  on  Celestial 
Monsters  the  celebrated  surgeon  Ambroise  Pare  de- 


FIG.  50. — What  our  Ancestors  saw  in  a  Comet. 

After  Ambrohe  Pare  (7528). 

scribes  this  awful  phenomenon  in  terms  anything  but 
seductive,  or  reassuring,  showing  us  the  menacing  sword 
surrounded  by  the  heads  it  had  cut  off  (Fig.  50). 

Our  fathers  saw  many  other  prodigies  in  the  skies; 
177 


Cavalry,  and  a  bloody  branch  crossing  the  sun,  June  u,  1554. 

FIG.  51. — Prodigies  seen  in  the  Heavens  by  our  Forefathers. 

178  ' 


THE  COMETS 

their  descendants,  less  credulous,  can  study  the  facsimile 
reproduced  in  Fig.  51,  of  the  drawings  published  in  the 
year  1557  by  Conrad  Lycosthenes  in  his  curious  Book 
of  Prodigies. 

So,  too,  it  is  asserted  that  Charles  V  renounced  the 
jurisdiction  of  his  Estates,  which  were  so  vast  that  "the 
Sun  never  slept  upon  them/'  because  he  was  terrified 
by  the  comet  of  1556  which  burned  in  the  skies  with  an 
alarming  brilliancy,  into  passing  the  rest  of  his  days  in 
prayer  and  devotion. 

It  is  certain  that  comets  often  exhibit  very  strange 
characteristics,  but  the  imagination  that  sees  in  them 
such  dramatic  figures  must  indeed  be  lively.  In  the 
Middle  Ages  and  the  Renaissance  these  were  swords  of 
fire,  bloody  crosses,  flaming  daggers,  etc.,  all  horrible 
objects  ready  to  destroy  our  poor  human  race! 

At  the  time  of  the  Romans,  Pliny  made  some  curious 
distinctions  between  them:  "The  Bearded  Ones  let 
loose  their  hair  like  a  majestic  beard;  the  Javelin  darts 
forth  like  an  arrow;  if  the  tail  is  shorter  and  ends  in  a 
point,  it  is  called  the  Sword;  this  is  the  palest  of  all 
the  Comets;  it  shines  like  a  sword,  without  rays;  the 
Plate  or  Disk  is  named  in  conformity  with  its  figure;  its 
color  is  amber,  the  Barrel  is  actually  shaped  like  a  barrel, 
as  it  might  be  in  smoke,  with  light  streaming  through  it; 
the  Horn  imitates  the  figure  of  a  horn  erected  in  the  sky, 
13  179 


ASTRONOMY  FOR  AMATEURS 

and  the  Lamp  that  of  a  burning  flame;  the  Equine  rep- 
resents a  horse's  mane,  shaken  violently  with  a  circu- 
lar motion.  There  are  bristled  comets;  these  resemble 
the  skins  of  beasts  with  the  fur  on  them,  and  are  sur- 
rounded by  a  nebulosity.  Lastly,  the  tails  of  certain 
comets  have  been  seen  to  menace  the  sky  in  the  form  of 
a  lance." 

These  hairy  orbs  that  appear  in  all  directions,  and 
whose  trajectories  are  sometimes  actually  perpendicular 
to  the  plane  of  the  ecliptic,  appear  to  obey  no  regular 
law.  Even  in  the  seventeenth  century  the  perspicacious 
Kepler  had  not  divined  their  true  character,  seeing  in 
them,  like  most  of  his  contemporaries,  emanations  from 
the  earth,  a  sort  of  vapor,  losing  itself  in  space.  These 
erratic  orbs  could  not  be  assimilated  with  the  other 
members  of  our  grand  solar  family  where,  generally 
speaking,  everything  goes  on  in  regular  order. 

And  even  in  our  own  times,  have  we  not  seen  the 
people  terrified  at  the  sight  of  a  flaming  comet  ?  Has 
not  the  end  of  the  world  by  the  agency  of  comets  been 
often  enough  predicted  ?  These  predictions  are  so  to 
speak  periodic;  they  crop  up  each  time  that  the  return 
of  these  cosmical  formations  is  announced  by  the  as- 
tronomers, and  always  meet  with  a  certain  number  of 
timid  souls  who  are  troubled  as  to  our  destinies. 


180 


THE  COMETS 

To-day  we  know  that  these  wanderers  are  subject 
to  the  general  laws  that  govern  the  universe.  The 
great  Newton  announced  that,  like  the  planets,  they 
were  obedient  to  universal  attraction;  that  they  must 
follow  an  extremely  elongated  curve,  and  return  period- 
ically to  the  focus  of  the  ellipse.  From  the  basis  of 
these  data  Halley  calculated  the  progress  of  the  comet 
of  1682,  and  ascertained  that  its  motions  presented  such 
similarity  with  the  apparitions  of  1531  and  1607,  that 
he  believed  himself  justified  in  identifying  them  and  in 
announcing  its  return  about  the  year  1759.  Faithful 
to  the  call  made  upon  it,  irresistibly  attracted  by  the  Orb 
of  Day,  the  comet,  at  first  pale,  then  ardent  and  incan 
descent,  returned  at  the  date  assigned  to  it  by  calcu 
lation,  three  years  after  the  death  of  the  illustrious 
astronomer.  Shining  upon  his  grave  it  bore  witness 
to  the  might  of  human  thought,  able  to  snatch  the  pro- 
foundest  secrets  from  the  Heavens! 

This  fine  comet  returns  every  seventy-six  years,  to 
be  visible  from  the  Earth,  and  has  already  been  seen 
twenty-four  times  by  the  astonished  eyes  of  man.  It 
appears,  however,  to  be  diminishing  in  magnitude.  Its 
last  appearance  was  in  1835,  and  we  shall  see  it  again 
in  1910,  a  little  sooner  than  its  average  period,  the  at-  . 
traction  of  Jupiter  having  this  time  slightly  accelerated 
its  course,  while  in  1759  it  retarded  it. 


ASTRONOMY  FOR  AMATEURS 

The  comets  thus  follow  a  very  elongated  orbit,  either 
elliptic,  turning  round  the  Sun,  or  parabolic,  dashing 
out  into  space.  In  the  first  case,  they  are  periodic 
(Fig.  52),  and  their  return  can  be  calculated.  In  the 
second  they  surprise  us  unannounced,  and  return  to 
the  abysses  of  eternity  to  reappear  no  more. 

Their  speed  is  even  greater  than  that  of  the  planets. 
it  is  equivalent  to  this,  multiplied  by  the  square  root 


FIG.  52. — The  orbit  of  a  Periodic  Comet. 

of  2,  that  is  to  say  by  1.414.  Thus  at  the  distance  of 
the  Earth  from  the  Sun  this  velocity  =  29,500  meters 
(18  miles)  per  second,  multiplied  by  the  above  number, 
that  is,  41,700  meters  (over  25  miles).  At  the  distance 
of  Mercury  it  =  47  X  1.414  or  66,400  meters  (over 
40  miles)  per  second. 

Among  the  numerous  comets  observed,  we  do  not  as 
yet  know  more  than  some  twenty  of  which  the  orbit  has 
been  determined.  Periodicity  in  these  bearded  orbs 

182 


THE  COMETS 

is  thus  exceptional,  if  we  think  of  the  innumerable  multi- 
tude of  comets  that  circle  through  the  Heavens.  Kepler 
did  not  exaggerate  when  he  said  "there  are  as  many 
comets  in  the  skies  as  there  are  fishes  in  the  sea."  These 
scouts  of  the  sidereal  world  constitute  a  regular  army, 
and  if  we  are  only  acquainted  with  the  dazzling  generals 
clad  in  gold,  it  is  because  the  more  modest  privates  can 
only  be  detected  in  the  telescope.  Long  before  the 
invention  of  the  latter,  these  wanderers  in  the  firmament 
roamed  through  space  as  in  our  own  day,  but  they  defied 
the  human  eye,  too  weak  to  detect  them.  Then  they 
were  regarded  as  rare  and  terrible  objects  that  no  one 
dared  to  contemplate.  To-day  they  may  be  counted  by 
hundreds.  They  have  lost  in  prestige  and  in  originality; 
but  science  is  the  gainer,  since  she  has  thus  endowed 
the  solar  system  with  new  members.  No  year  passes 
without  the  announcement  of  three  or  four  new  arrivals. 
But  the  fine  apparitions  that  attract  general  attention 
by  their  splendor  are  rare  enough. 

These  eccentric  visitors  do  not  resemble  the  planets, 
for  they  have  no  opaque  body  like  the  Earth,  Venus, 
Mars,  or  any  of  the  rest.  They  are  transparent  nebu- 
losities, of  extreme  lightness,  without  mass  nor  density. 
We  have  just  photographed  the  comet  of  the  moment, 
July,  1903:  the  smallest  stars  are  visible  through  its  tail, 
and  even  through  the  nucleus.] 

183 


ASTRONOMY  FOR  AMATEURS 

They  arrive  in  every  direction  from  the  depths  of 
space,  as  though  to  reanimate  themselves  in  the  burning, 
luminous,  electric  solar  center. 

Attracted  by  some  potent  charm  toward  this  daz- 
zling focus,  they  come  inquisitive  and  ardent,  to  warm 
themselves  at  its  furnace.  At  first  pale  and  feeble,  they 
are  born  again  when  the  Sun  caresses  them  with  his 
fervid  heat.  Their  motions  accelerate,  they  haste  to 
plunge  wholly  into  the  radiant  light.  At  length  they 
burst  out  luminous  and  superb,  when  the  day-star  pene- 
trates them  with  his  burning  splendor,  illuminates  them 
with  a  marvelous  radiance,  and  crowns  them  with  glory. 
But  the  Sun  is  generous.  Having  showered  benefits 
upon  these  gorgeous  celestial  butterflies  that  flutter 
round  him  as  round  some  altar  of  the  gods,  he  grants 
them  liberty  to  visit  other  heavens,  to  seek  fresh  uni- 
verses. .  .  . 

The  original  parabola  is  converted  into  an  ellipse, 
if  the  imprudent  adventurer  in  returning  to  the  Sun 
passes  near  some  great  planet,  such  as  Jupiter,  Saturn, 
Uranus,  or  Neptune,  and  suffers  its  attraction.  It  is 
then  imprisoned  by  our  system,  and  can  no  longer  es- 
cape from  it.  After  reenforcement  at  the  solar  focus, 
it  must  return  to  the  identical  point  at  which  it  felt  the 
first  pangs  of  a  new  destiny.  Henceforward,  it  belongs 
to  our  celestial  family,  and  circles  in  a  closed  curve, 

184 


THE  COMETS 

otherwise,  it  is  free  to  continue  its  rapid  course  toward 
other  suns  and  other  systems. 

As  a  rule,  the  telescope  shows  three  distinct  parts  in 
a  comet.  There  is  first  the  more  brilliant  central  point, 
or  nucleus,  surrounded  by  a  nebulosity  called  the  hair, 
or  brush,  and  prolonged  in  a  luminous  appendix  stretch- 
ing out  into  the  tail.  The  head  of  the  comet  is  the  brush 
and  the  nucleus  combined. 


FIG.  53 The  tails  of  Comets  are  opposed  to  the  Sun. 

It  is  usually  supposed  that  the  tail  of  a  comet  follows 
it  throughout  the  course  of  its  peregrinations.  Nothing 
of  the  kind.  The  appendix  may  even  precede  the 
nucleus;  it  is  always  opposite  the  Sun, — that  is  to  say,  it 
is  situated  on  the  prolongation  of  a  straight  line,  starting 
from  the  Sun,  and  passing  through  the  nucleus  (Fig.  53). 
The  tail  does  not  exist,  so  long  as  the  comet  is  at  a 
distance  from  the  orb  of  day;  but  in  approaching  the 
Sun,  the  nebulosity  is  heated  and  dilates,  giving  birth 

185 


ASTRONOMY  FOR  AMATEURS 

to  those  mysterious  tails  and  fantastic  streamers  whose 
dimensions  vary  considerably  for  each  comet.  The 
dilations  and  transformations  undergone  by  the  tail 
suggest  that  they  may  be  due  to  a  repulsive  force  emana- 
ting from  the  Sun,  an  electric  charge  transmitted  doubt- 
less through  the  ether.  It  is  as  though  Phoebus  blew 
upon  them  with  unprecedented  force. 

Telescopic  comets  are  usually  devoid  of  tail,  even 
when  they  reach  the  vicinity  of  the  Sun.  They  appear 
as  pale  nebulosities,  rounded  or  oval,  more  condensed 
toward  the  center,  without,  however,  showing  any  dis- 
tinct nucleus.  These  stars  are  only  visible  for  a  minute 
fraction  of  their  course,  when  they  reach  a  point  not  far 
from  the  Sun  and  the  terrestrial  orbit. 

The  finest  comets  of  the  last  century  were  those  of 
1811,  1843,  1858,  1861,  1874,  1880,  1881,  and  1882. 
The  Great  Comet  of  1811,  after  spreading  terror  over 
certain  peoples,  notably  in  Russia,  became  the  provi- 
dence of  the  vine-growers.  As  the  wine  was  particu- 
larly good  and  abundant  that  year,  the  peasants  at- 
tributed this  happy  result  to  the  influence  of  the  celestial 
visitant. 

In  1843  one  of  these  strange  messengers  from  the 
Infinite  appeared  in  our  Heavens.  It  was  so  brilliant 
that  it  was  visible  in  full  daylight  on  February  28th, 
alongside  of  the  Sun.  This  splendid  comet  was  ac- 

186 


THE  COMETS 

companied  by  a  marvelous  rectilinear  tail  measuring 
300,000,000  kilometers  (186,000,000  miles)  in  length, 
and  its  flight  was  so  rapid  that  it  turned  the  solar  hemi- 
sphere at  perihelion  in  two  hours,  representing  a  speed  of 
550  kilometers  (342  miles)  a  second. 

But  the  most  curious  fact  is  that  this  radiant  ap- 
parition passed  so  near  the  Sun  that  it  must  have 
traversed  its  flames,  and  yet  emerged  from  them  safe 
and  sound. 

Noteworthy  also  was  the  comet  of  1858  (Fig.  49), 
discovered  at  Florence  by  Donati.  Its  tail  extended  to 
a  length  of  90,000,000  kilometers  (55,900,000  miles), 
and  its  nucleus  had  a  diameter  of  at  least  900  kilo- 
meters (559  miles).  It  is  a  curious  coincidence  that  the 
wine  was  remarkably  excellent  and  abundant  in  that 
year  also. 

The  comet  of  1861  almost  rivaled  the  preceding. 

Coggia's  Comet,  in  1874,  was  also  remarkable  for  its 
brilliancy,  but  was  very  inferior  to  the  last  two.  Finally, 
the  latest  worthy  of  mention  appeared  in  1882.  This 
magnificent  comet  also  touched  the  Sun,  traveling  at  a 
speed  of  480  kilometers  (299  miles)  per  second.  It 
crossed  the  gaseous  atmosphere  of  the  orb  of  day,  and 
then  continued  its  course  through  infinity.  On  the  day 
of,  and  that  following,  its  perihelion,  it  could  be  detected 
with  the  unaided  eye  in  full  daylight,  enthroned  in  the 

187 


ASTRONOMY  FOR  AMATEURS 

Heavens  beside  the  dazzling  solar  luminary.     For  the 
rest,  it  was  neither  that  of  1858  nor  of  1861. 

Since  1882  we  have  not  been  favored  with  a  visit 
from  any  fine  comet;  but  we  are  prepared  to  give  any 
such  a  reception  worthy  of  their  magnificence:  first, 
because  now  that  we  have  fathomed  them  we  are  no 
longer  awestruck ;  second,  because  we  would  gladly 
study  them  more  closely. 

In  short,  these  hirsute  stars,  whose  fantastic  ap- 
pearance impressed  the  imagination  of  our  ancestors 
so  vividly,  are  no  longer  formidable.  Their  mass  is 
inconsiderable;  they  seem  to  consist  mainly  of  the  light- 
est of  gases.  Analysis  of  their  incandescence  reveals  a 
spectrum  closely  resembling  that  of  many  nebulae;  the 
presence  of  carbon  is  more  particularly  obvious.  Even 
the  nucleus  is  not  solid,  and  is  often  transparent. 

It  is  fair  to  say  that  the  action  of  a  comet  might  be 
deleterious  if  one  of  these  orbs  were  to  arrive  directly 
upon  us.  The  transformation  of  motion  into  heat,  and 
the  combination  of  the  cometary  gases  with  the  oxygen 
of  our  atmosphere  might  produce  a  conflagration,  or  a 
general  poisoning  of  the  atmosphere. 

But  the  collision  of  a  comet  with  a  planet  is  almost 
an  impossibility.  This  phenomenon  could  only  occur 
if  the  comet  crossed  the  planetary  orbit  at  the  exact 

188 


THE  COMETS 

moment  at  which  the  planet  was  passing.  When  we 
think  of  the  immensity  of  space,  of  the  extraordinary 
length  of  way  traversed  by  a  world  in  its  annual  journey 
round  the  Sun,  and  the  speed  of  its  rotation,  we  see 
why  this  coincidence  is  hardly  likely  to  occur.  Thus, 
among  the  hundreds  of  comets  catalogued,  a  few  only 
cut  the  terrestrial  orbit.  One  of  them,  that  of  1832, 
traversed  the  path  of  our  globe  in  the  nights  of  October 
29  and  30  in  that  year;  but  the  Earth  only  passed  the 
same  point  thirty  days  later,  and  at  the  critical  period 
was  more  than  80,000,000  kilometers  (50,000,000  miles) 
away  from  the  comet. 

On  June  30,  1861,  however,  the  Earth  passed  through 
the  extremity  of  the  tail  of  the  Great  Comet  of  that  year. 
No  one  even  noticed  it.  The  effects  were  doubtless  quite 
immaterial. 

In  1872  we  were  to  collide  with  Biela's  Comet,  lost 
since  1852;  now,  as  we  shall  presently  see,  we  came  with 
flying  colors  out  of  that  disagreeable  situation,  because 
the  comet  had  disintegrated,  and  was  reduced  to  powder. 
So  we  may  sleep  in  peace  as  regards  future  danger 
likely  to  come  to  us  from  comets.  There  is  little  fear 
of  the  destruction  of  humanity  by  these  windy  bags. 

These  ethereal  beauties  whose  blond  locks  float 
carelessly  upon  the  azure  night  are  not  concerned  with 
us;  they  seem  to  have  no  other  preoccupation  than  to 

189 


ASTRONOMY  FOR  AMATEURS 

race  from  sun  to  sun,  visiting  new  Heavens,  indifferent 
to  the  astonishment  they  produce  in  us.  They  speed 
restlessly  and  tirelessly  through  infinity;  they  are  the 
Amazons  of  space. 

What  suns,  what  worlds  must  they  have  visited 
since  the  moment  of  their  birth!  If  these  splendid 
fugitives  could  relate  the  story  of  their  wanderings, 
how  gladly  should  we  listen  to  the  enchanting  descrip- 
tions of  the  various  abodes  they  have  journeyed  to! 
But  alas!  these  mysterious  explorers  are  dumb;  they 
tell  none  of  their  secrets,  and  we  must  needs  respect 
their  enigmatic  silence. 

Yet,  some  of  them  have  left  us  a  modest  token  of 
remembrance,  an  almost  impalpable  nothing,  sufficient, 
however,  to  enable  us  to  address  our  thanks  to  the  con- 
siderate messenger. 

Can  there  be  any  one  upon  the  Earth  who  has  not 
been  struck  by  the  phosphorescent  lights  that  glide 
through  the  somber  night,  leaving  a  brilliant  silver  or 
golden  track — the  luminous,  ephemeral  trail  of  a  meteor  ? 

Sometimes,  when  Night  has  silently  spread  the  im- 
mensity of  her  wings  above  the  weary  Earth,  a  shining 
speck  is  seen  to  detach  itself  in  the  shades  of  evening 
from  the  starry  vault,  shooting  lightly  through  the  con- 
stellations to  lose  itself  in  the  infinitude  of  space. 

190 


THE  COMETS 

These     bewitching    sparks    attract    our    eyes     and 
chain  our  senses.*     Fascinating  celestial    fireflies,  their 


FIG.  54. — A  Meteor. 
191 


ASTRONOMY  FOR  AMATEURS 

dainty  flames  dart  in  every  direction  through  space, 
sowing  the  fine  dust  of  their  gilded  wings  upon  the  fields 
of  Heaven.  They  are  born  to  die;  their  life  is  only  a 
breath;  yet  the  impression  which  they  make  upon  the 
imagination  of  mortals  is  of  the  profoundest. 

The  young  girl  dreaming  in  the  delicious  tranquillity 
of  the  transparent  night  smiles  at  this  charming  sister 
in  the  Heavens  (Fig.  54).  What  can  not  this  adorable 
star  announce  to  the  tender  and  loving  heart  ?  Is  it 
the  shy  messenger  of  the  happiness  so  long  desired  ? 
Its  unpremeditated  appearance  fills  the  soul  with  a  ray 
of  hope  and  makes  it  tremble.  It  is  a  golden  beam  that 
glides  into  the  heart,  expanding  it  in  the  thrills  of  a 
sudden  and  ephemeral  pleasure.  .  .  .  The  radiant  meteor 
seems  to  quit  the  velvet  of  the  deep  blue  sky  to  respond 
to  the  appeal  of  the  imploring  voice  that  seeks  its  succor. 

What  secrets  has  it  not  surprised!  And  who  bears 
malice  against  it  ?  It  is  the  friend  of  the  betrothed  who 
invoke  its  passage  to  confide  their  wishes,  and  associate 
it  with  their  dreams.  Tradition  holds  that  if  a  wish 
be  formulated  during  the  visible  passage  of  a  meteor  it 
will  certainly  be  fulfilled  before  the  year  is  out.  Be- 
tween ourselves,  however,  this  is  but  a  surviving  figment 
of  the  ancestral  imagination,  for  this  celestial  jewel  takes 
no  such  active  part  in  the  doings  of  Humanity.  .  .  . 
Besides,  try  to  express  a  wish  distinctly  in  a  second! 

192 


THE  COMETS 

It  is  a  curious  fact  that  while  comets  have  so  often 
spread  terror  on  the  Earth,  shooting  stars  should  on  the 
contrary  have  been  regarded  with  benevolent  feelings 
at  all  times.  And  what  is  a  shooting  star  ?  These 
dainty  excursionists  from  the  celestial  shores  are  not,  as 
is  supposed,  true  stars.  They  are  atoms,  nothings, 
minute  fragments  deriving  in  general  from  the  disin- 
tegration of  comets.  They  come  to  us  from  a  vast 
distance,  from  millions  on  millions  of  miles,  and  circle 
in  swarms  around  the  Sun,  following  a  very  elongated 
ellipse  which  closely  resembles  that  of  the  cometary  orbit. 
Their  flight  is  extremely  rapid,  reaching  sometimes  more 
than  40  kilometers  (25  miles)  per  second,  a  cometary 
speed  that  is,  as  we  have  seen,  greatly  above  that  of  our 
terrestrial  vehicle,  which  amounts  to  29  to  30  kilometers 
(about  19  miles). 

These  little  corpuscles  are  not  intrinsically  luminous-, 
but  when  the  orbit  of  a  swarm  of  meteors  crosses  our 
planet,  a  violent  shock  arises,  the  speed  of  which  may  be 
as  great  as  72  kilometers  (45  miles)  in  the  first  second 
if  we  meet  the  star  shower  directly;  the  average  rate, 
however,  does  not  exceed  30  to  40  kilometers  (19  to  25 
miles),  for  these  meteors  nearly  always  cross  our  path 
obliquely.  The  height  at  which  they  arrive  is  usually 
no  kilometers  (68  miles),  and  80  kilometers  (50  miles) 
at  the  moment  of  disappearance  of  the  meteor;  but 

193 


ASTRONOMY  FOR  AMATEURS 

shooting  stars  have  been  observed  at  300  kilometers 
(186  miles). 

The  friction  caused  by  this  collision  high  up  in  the 
atmosphere  transforms  the  motion  into  heat.  The 
molecules  incandesce,  and  burn  like  true  stars  with  a 
brilliancy  that  is  often  magnificent. 

But  their  glory  is  of  short  duration.  The  excessive 
heat  resulting  from  the  shock  consumes  the  poor  firefly; 
its  remains  evaporate,  and  drop  slowly  to  the  Earth, 
where  they  are  deposited  on  the  surface  of  the  soil  in  a 
sort  of  ferruginous  dust  mixed  with  carbon  and  nickel. 
Some  one  hundred  and  forty-six  milliards  of  them  reach 
us  annually,  as  seen  by  the  unaided  eye,  and  many  more 
in  the  telescope;  the  effect  of  these  showers  of  meteoric 
matter  is  an  insensible  increase  in  the  mass  of  our  globe, 
a  slight  lessening  of  its  rotary  motion,  and  the  acceleration 
of  the  lunar  movements  of  revolution. 

Although  the  appearance  of  shooting  stars  is  a  com- 
mon enough  phenomenon,  visible  every  night  of  the  year, 
there  are  certain  times  when  they  arrive  in  swarms, 
from  different  quarters  of  the  sky.  The  most  remark- 
able dates  in  this  connection  are  the  night  of  August 
loth  and  the  morning  of  November  I4th.  Every  one 
knows  the  shooting  stars  of  August  loth,  because  they 
arrive  in  the  fine  warm  summer  evenings  so  favorable 
to  general  contemplation  of  the  Heavens.  The  phe- 

194 


THE  COMETS 

nomenon  lasts  till  the  I2th,  and  even  beyond,  but  the 
maximum  is  on  the  loth.  When  the  sky  is  very  clear, 
and  there  is  no  moon,  hundreds  of  shooting  stars  can 
be  counted  on  those  three  nights,  sometimes  thousands. 
They  all  seem  to  come  from  the  same  quarter  of  the 
Heavens,  which  is  called  the  radiant,  and  is  situated 
for  the  August  swarm  in  the  constellation  of  Perseus, 
whence  they  have  received  the  name  of  Perseids.  Our 
forefathers  also  called  them  the  tears  of  St.  Lawrence, 
because  the  feast  of  that  saint  is  on  the  same  date. 
These  shooting  stars  describe  a  very  elongated  ellipse, 
and  their  orbit  has  been  identified  with  that  of  the 
Great  Comet  of  1862. 

The  shower  of  incandescent  asteroids  on  November 
1 4th  is  often  much  more  abundant  than  the  preceding. 
In  1799,  1833,  and  1866,  the  meteors  were  so  numerous 
that  they  were  described  as  showers  of  rain,  especially  on 
the  first  two  dates.  For  several  hours  the  sky  was  fur- 
rowed with  falling  stars.  An  English  mariner,  Andrew 
Ellicot,  who  made  the  drawing  we  reproduce  (Fig.  55), 
described  the  phenomenon  as  stupendous  and  alarming 
(November  12,  1799,  3  A.  M.).  The  same  occurred  on 
November  13,  1833.  The  meteors  that  scarred  the 
Heavens  on  that  night  were  reckoned  at  240,000.  These 
shooting  stars  received  the  name  of  Leonids,  because 
their  radiant  is  situated  in  the  constellation  of  the  Lion. 
14 


ASTRONOMY  FOR  AMATEURS 

This  swarm  follows  the  same  orbit  as  the  comet  of 
1866,  which  travels  as  far  as  Uranus,  and  comes  back  to 


FIG.  55. — Shooting  Stars  of  November  12,  1799. 

From  a  contemporary  draivlng. 
196 


THE  COMETS 

the  vicinity  of  the  Sun  every  thirty-three  years.  Hence 
we  were  entitled  to  expect  another  splendid  apparition 
in  1899,  but  the  expectations  of  the  astronomers  were 
disappointed.  All  the  preparations  for  the  appropriate 
reception  of  these  celestial  visitors  failed  to  bring  about 
the  desired  result.  The  notes  made  in  observatories, 
or  in  balloons,  admitted  of  the  registration  of  only  a  very 
small  number  of  meteors.  The  maximum  was  thirteen. 
During  that  night,  some  200  shooting  stars  were  counted. 
There  were  more  in  1900,  1901,  and,  above  all,  in  1902. 
This  swarm  has  become  displaced. 

The  night  of  November  2/th  again  is  visited  by  a 
number  of  shooting  stars  that  are  the  disaggregated  re- 
mains of  the  Comet  of  Biela.  This  comet,  discovered 
by  Biela  in  1827,  accomplished  its  revolution  in  six 
and  a  half  years,  and  down  to  1846  it  responded  punc- 
tually to  the  astronomers  who  expected  its  return  as 
fixed  by  calculation.  But  on  January  13,  1846,  the 
celestial  wanderer  broke  in  half:  each  fragment  went 
its  own  way,  side  by  side,  to  return  within  sight  from 
the  Earth  in  1852.  It  was  their  last  appearance. 
That  year  the  twin  comets  could  still  be  seen,  though 
pale  and  insignificant.  Soon  they  vanished  into  the 
depths  of  night,  and  never  appeared  again.  They  were 
looked  for  in  vain,  and  were  despaired  of,  when  on 
November  27,  1872,  instead  of  the  shattered  comet, 

197 


ASTRONOMY  FOR  AMATEURS 

came  a  magnificent  rain  of  shooting  stars.  They  fell 
through  the  Heavens,  numerous  as  the  flakes  of  a 
shower  of  snow. 

The  same  phenomenon  recurred  on  November  27, 
1885,  and  confirmed  the  hypothesis  of  the  demoli- 
tion and  disaggregation  of  Biela's  Comet  into  shooting 
stars. 

There  is  an  immense  variety  in  the  brilliancy  of  the 
shooting  stars,  from  the  weak  telescopic  sparks  that 
vanish  like  a  flash  of  lightning,  to  the  incandescent 
bolides  or  fire-balls  that  explode  in  the  atmosphere. 

Fig.  56  shows  an  example  of  these,  and  it  represents 
a  fire-ball  observed  at  the  Observatory  of  Juvisy  on  the 
night  of  August  10,  1899.  It  arrived  from  Cassiopeia, 
and  burst  in  Cepheus. 

This  phenomenon  may  occur  by  day  as  well  as  by 
night.  It  is  often  accompanied  by  one  or  several  ex- 
plosions, the  report  of  which  is  sometimes  perceptible 
to  a  considerable  distance,  and  by  a  shower  of  meteorites. 
The  globe  of  fire  bursts,  and  splits  up  into  luminous  frag- 
ments, scattered  in  all  directions.  The  different  parts  of 
the  fire-ball  fall  to  the  surface  of  the  Earth,  under  the 
name  of  aerolites,  or  rather  of  uranoliths,  since  they 
arrive  from  the  depths  of  space,  and  not  from  our 
atmosphere. 

198 


THE  COMETS 

From  the  most  ancient  times   we  hear  of  showers 
of  uranoliths  to  which   popular  superstitions  were  at- 


FIG.  56. — Fire-Bali  seen  from  the  Observatory  at  Juvisy, 
August  10,  1899. 

tached;  and  the  Greeks  even  gave  the  name  of  Sideros 
to  iron,  the  first  iron  used  having  been  sidereal. 

199 


ASTRONOMY  FOR  AMATEURS 

No  year  passes  without  the  announcement  of  several 
showers  of  uranoliths,  and  the  phenomenon  sometimes 


FIG.  57. — Explosion  of  a  Fire-Bail  above  Madrid, 
February  I  o,  i 


causes  great  alarm  to  those  who  witness  it.  One  of  the 
most  remarkable  explosions  is  that  which  occurred  above 
Madrid,  February  10,  1896,  a  fragment  from  which, 

200 


THE  COMETS 

sent  me  by  M.  Arcimis,  Director  of  the  Meteorological 
Institute,  fell  immediately  in  front  of  the  National 
Museum  (Fig.  57).  The  phenomenon  occurred  at 
9.30  A.  M.,  in  brilliant  sunshine.  The  flash  of  the  ex- 
plosion was  so  dazzling  that  it  even  illuminated  the  in- 
terior of  the  houses;  an  alarming  clap  of  thunder  was 
heard  seventy  seconds  after,  and  it  was  believed  that  an 
explosion  of  dynamite  had  occurred.  The  fire-ball  burst 
at  a  height  of  fourteen  miles,  and  was  seen  as  far  as 
435  miles  from  Madrid! 

In  one  of  Raphael's  finest  pictures  (The  Madonna  of 
Folignd)  a  fire-ball  may  be  seen  beneath  a  rainbow 
(Fig.  58),  the  painter  wishing  to  preserve  the  remem- 
brance of  it,  as  it  fell  near  Milan,  on  September  4,  1511. 
This  picture  dates  from  1512. 

The  dimensions  of  these  meteorites  vary  consider- 
ably; they  are  of  all  sizes,  from  the  impalpable  dust 
that  floats  in  the  air,  to  the  enormous  blocks  exposed  in 
the  Museum  of  Natural  History  in  Paris.  Many  of 
them  weigh  several  million  pounds.  That  represented 
below  fell  in  Mexico  during  the  shower  of  meteors  of 
November  27,  1885.  It  weighed  about  four  pounds. 

These  bolides  and  uranoliths  come  to  us  from  the 
depths  of  space;  but  they  do  not  appear  to  have  the  same 
origin  as  the  shooting  stars.  They  may  arise  from 
worlds  destroyed  by  explosion  or  shock,  or  even  from 

201 


ASTRONOMY  FOR  AMATEURS 

planetary  volcanoes.     The  lightest  of  them  may  have 
been  expelled  from  the  volcanoes  of  the  Moon.     Some 


FIG.  58.— Raphael's  Fire-Bali  (The  Madonna  of  Foligno). 
202 


THE  COMETS 

of  the  most  massive,  in  which  iron  predominates,  may 
even  have  issued  from  the  bowels  of  the  Earth,  projected 
into  space  by  some  volcanic  explosion,  at  an  epoch  when 
our  globe  was  perpetually  convulsed  by  cataclysms  of 
extraordinary  violence.  They  return  to  us  to-day  after 


FIG.  59. — A  Uranolith. 

being  removed  from  the  Earth  to  distances  proportional 
to  the  initial  speed  imparted  to  them.  This  origin  seems 
the  more  admissible  as  the  stones  that  fall  from  the  skies 
exhibit  a  mineral  composition  identical  with  that  of  the 
terrestrial  materials. 

203 


ASTRONOMY  FOR  AMATEURS 

In  any  case,  these  uranoliths  bring  us  back  at  least 
by  their  fall  to  our  Earth,  and  from  henceforward  we  will 
remain  upon  it,  to  study  its  position  in  space,  and  to  take 
account  of  the  place  it  fills  in  the  Universe,  and  of  the 
astronomical  laws  that  govern  our  destiny. 


204 


CHAPTER  VIII 
THE  EARTH 

OUR  grand  celestial  journey  lands  us  upon  our  own 
little  planet,  on  this  globe  that  gravitates  between  Mars 
and  Venus  (between  War  and  Love),  circulating  like 
her  brothers  of  the  solar  system,  around  the  colossal 
Sun. 

The  Earth!  The  name  evokes  in  us  the  image  of 
Life,  and  calls  up  the  theater  of  our  activities,  our  ambi- 
tions, our  joys  and  sorrows.  Does  it  not,  in  fact,  to 
ignorant  eyes,  represent  the  whole  of  the  universe  ? 

And  yet,  what  is  the  Earth  ? 

The  Earth  is  a  star  in  the  Heavens.  We  learned 
this  much  in  our  first  lesson.  It  is  a  globe  of  opaque 
material,  similar  to  the  planets  Mercury,  Venus,  Mars, 
Jupiter,  etc.,  as  previously  described.  Isolated  on  all 
sides  in  space,  it  revolves  round  the  Sun,  along  a  vast 
orbit  that  it  accomplishes  in  a  year.  And  while  it  thus 
glides  along  the  lines  of  solar  attraction,  the  terrestrial 
ball  rotates  rapidly  upon  itself  in  twenty-four  hours. 

These  statements  may  appear  dubious  at  first  sight, 
and  contradictory  to  the  evidence  of  our  senses. 

205 


ASTRONOMY  FOR  AMATEURS 

Now  that  the  surface  of  the  Earth  has  been  explored 
in  all  directions,  there  is  no  longer  room  to  doubt  that  it 
is  a  globe,  a  sort  of  ball  that  we  adhere  to.  A  journey 
round  the  world  is  common  enough  to-day,  and  always 
yields  the  most  complete  evidence  of  the  spherical  nature 
of  the  Earth.  On  the  other  hand,  the  curvature  of  the 
seas  is  a  no  less  certain  proof.  When  a  ship  reaches  the 
dark-blue  line  that  appears  to  separate  the  sky  from  the 
ocean,  it  seems  to  be  hanging  on  the  horizon.  Little 
by  little,  however,  as  it  recedes,  it  drops  below  the  hori- 
zon line;  the  tops  of  the  masts  being  the  last  to  disap- 
pear. The  observer  on  board  ship  witnesses  the  same 
phenomenon.  The  low  shores  are  first  to  disappear, 
while  the  high  coasts  and  mountains  are  much  longer 
visible. 

The  aspect  of  the  Heavens  gives  another  proof  of 
the  Earth's  rotundity.  As  one  travels  North  or  South, 
new  stars  rise  higher  and  higher  above  the  horizon  in 
the  one  direction  or  the  other,  and  those  which  shine  in 
the  latitude  one  is  leaving,  gradually  disappear.  If  the 
surface  of  the  Earth  were  flat,  the  ships  on  the  sea  would 
be  visible  as  long  as  our  sight  could  pierce  the  distance, 
and  all  the  stars  of  the  Heavens  would  be  equally  visible 
from  the  different  quarters  of  the  world. 

Lastly,  during  the  eclipses  of  the  Moon,  the  shadow 
projected  by  the  Earth  upon  our  satellite  is  always  round. 

206 


THE  EARTH 

This  is  another  proof  of  the  spherical  nature  of  the  ter- 
restrial globe. 

We  described  the  Earth  as  an  orb  in  the  Heavens, 
similar  to  all  the  other  planets  of  the  great  solar  family. 
We  see  these  sister  planets  of  our  world  circulating  under 
the  starry  vault,  like  luminous  points  whose  brilliancy 
is  sometimes  dazzling.  For  us  they  are  marvelous 
celestial  birds  hovering  in  the  ether,  upheld  by  invisible 
wings.  The  Earth  is  just  the  same.  It  is  supported 
by  nothing.  Like  the  soap-bubble  that  assumes  a 
lovely  iridescence  in  the  rays  of  the  Sun,  or,  better,  like 
the  balloon  rapidly  cleaving  the  air,  it  is  isolated  from 
every  kind  of  support. 

Some  minds  have  difficulty  in  conceiving  this  isola- 
tion, because  they  form  a  false  notion  of  weight. 

The  astronomers  of  antiquity,  who  divined  it,  knew 
not  how  to  prevent  the  Earth  from  falling.  They  asked 
anxiously  what  the  strong  bands  capable  of  holding  up 
this  block  of  no  inconsiderable  weight  could  be.  At 
first  they  thought  it  floated  on  the  waters  like  an  island. 
Then  they  postulated  solid  pillars,  or  even  supposed  it 
might  turn  on  pivots  placed  at  the  poles.  But  on  what 
would  all  these  imaginary  supports  have  rested  ?  All 
these  fanciful  foundations  of  the  Earth  had  to  be  given 
up,  and  it  was  recognized  as  a  globe,  isolated  in  every 
part.  This  illusion  of  the  ancients,  which  still  obtains 

207 


ASTRONOMY  FOR  AMATEURS 

for  a  great  many  citizens  of  our  globule,  arises,  as  we 
said,  from  a  false  conception  of  weight. 

Weight  and  attraction  are  one  and  the  same  force. 

A  body  can  only  fall  when  it  is  attracted,  drawn  by  a 
more  important  body.  Now,  in  whatever  direction  we 
may  wander  lipon  the  globe,  our  feet  are  always  down- 
ward. Down  is  therefore  the  center  of  the  Earth. 

The  terrestrial  globe  may  be  regarded  as  an  im- 
mense ball  of  magnet,  and  its  attraction  holds  us  at  its 
surface.  We  weigh  toward  the  center.  We  may  travel 
over  this  surface  in  all  directions  ;  our  feet  will  always 
be  below,  whatever  the  direction  of  our  steps.  For  us, 
"below"  is  the  inside  of  our  planet,  arid  " above "  is 
the  immensity  of  the  Heavens  that  extend  above  our 
heads,  right  round  the  globe. 

This  once  understood,  where  could  the  Earth  fall  to  ? 
The  question  is  an  absurdity.  "Below"  being  toward 
the  center,  it  would  have  to  fall  out  of  itself. 

Let  us  then  picture  the  Earth  as  a  vast  sphere,  de- 
tached from  all  that  exists  around  it,  in  the  infinity  of 
the  Heavens.  A  point  diametrically  opposed  to  another 
is  called  its  antipodes.  New  Zealand  is  approximately 
the  antipodes  to  France.  Well,  for  the  inhabitants  of 
New  Zealand  and  of  France  the  top  is  reciprocally 
opposed,  and  the  bottom,  or  the  feet,  are  diametrically 
in  opposition.  And  yet,  for  one  as  for  the  other,  the 

208 


THE  EARTH 

bottom  is  the  soil  they  are  held  to,  and  the  top  is  space 
above  their  heads. 

The  Earth  turns  on  itself  in  twenty-four  hours. 
Whatever  is  above  us,  e.  g.,  at  midday,  we  call  high; 
twelve  hours  later,  at  midnight,  we  give  the  same  quali- 
fication to  the  part  of  space  that  was  under  our  feet  at 
noon.  What  is  in  the  sky,  and  over  our  heads,  at  a  given 
hour,  is  under  our  feet,  and  yet  always  in  the  sky,  twelve 
hours  later.  Our  position,  in  relation  to  the  space  that 
surrounds  us,  changes  from  hour  to  hour,  and  "top" 
and  "bottom"  vary  also,  relatively  to  our  position. 

Our  planet  is  thus  a  ball,  slightly  flattened  at  the 
poles  (by  about  ^\-^}.  Its  diameter,  at  the  equator,  is 
12,742  kilometers  (7,926  miles);  from  one  pole  to  the 
other  is  a  little  less,  owing  to  the  flattening  of  the  polar 
caps.  The  difference  is  some  43  kilometers  (about 
27  miles). 

Its  circumference  is  40,000  kilometers  (24,900  miles). 
This  ball  is  surrounded  by  an  aerial  envelope,  the  atmos- 
phere, the  height  of  which  can  not  be  less  than  300  kilo- 
meters (186  miles),  according  to  the  observations  made 
on  certain  shooting  stars. 

We  all  know  that  this  layer  of  air,  at  the  bottom  of 
which  we  live,  is  a  beautiful  azure  blue  that  seems  to 
separate  us  from  the  sidereal  abyss,  spreading  over  our 
heads  in  a  kind  of  vault  that  is  often  filled  with  clouds, 

209 


ASTRONOMY  FOR  AMATEURS 

and  giving  the  illusion  of  resting  far  off  on  the  circle  of 
the  horizon.  But  this  is  only  an  illusion.  In  reality, 
there  is  neither  vault  nor  horizon;  space  is  open  in  all 
directions.  If  the  atmosphere  did  not  exist,  or  if  it  were 
completely  transparent,  we  should  see  the  stars  by  day 
as  by  night,  for  they  are  continually  round  us,  at  noon 
as  at  midnight,  and  we  can  see  them  in  the  full  daylight, 
with  the  help  of  astronomical  instruments.  In  fact, 
certain  stars  (the  radiant  Venus  and  the  dazzling  Jupi- 
ter) pierce  the  veil  of  the  atmosphere,  and  are  visible 
with  the  unaided  eye  in  full  daylight. 

The  terrestrial  surface  is  510,000,000  square  kilo- 
meters (200,000,000  square  miles).  The  waters  of  the 
ocean  cover  three-quarters  of  this  surface,  i.  e.y  383,200,- 
ooo  square  kilometers  (150,000,000  square  miles),  and 
the  continents  only  occupy  136,600,000  square  kilo- 
meters (55,000  square  miles)c  France  represents  about 
the  thousandth  part  of  the  total  superficies  of  the  globe. 

Despite  the  asperities  of  mountain  ranges,  and  the 
abysses  hollowed  out  by  the  waters,  the  terrestrial  globe 
is  fairly  regular,  and  in  relation  to  its  volume  its  surface 
is  smoother  than  that  of  an  orange.  The  highest  sum- 
mits of  the  Himalaya,  the  profoundest  depths  of  the 
somber  ocean,  do  not  attain  to  the  millionth  part  of 
its  diameter. 

In  weight,  the  Earth  is  five  and  a  half  times  heavier 
2IO 


THE  EARTH 

than  would  be  a  globe  of  water  of  the  same  dimensions, 
That  is  to  say: 

6,957,930,000,000,000,000,000,000  kilograms 
(6,833,000,000,000,000,000,000  tons). 

The  atmospheric  atmosphere  with  which  it  is  sur- 
rounded represents. 

6,263,000,000,000,000,000  kilograms 
(6,151,000,000,000,000  tons). 

Each  of  us  carries  an  average  weight  of  some  17,000 
kilograms  (16  tons)  upon  his  shoulders.  Perhaps  some 
one  will  ask  how  it  is  that  we  are  not  crushed  by  this 
weight,  which  is  out  of  all  proportion  with  our  strength, 
but  to  which,  nevertheless,  we  appear  insensible.  It  is 
because  the  aerial  fluid  enclosed  within  our  bodies 
exerts  a  pressure  equal  and  opposite  to  the  external 
atmospheric  pressure,  and  these  pressures  are  at  equi- 
librium. 

The  Earth  is  characterized  by  no  essential  or  par- 
ticular differences  relatively  to  the  other  worlds  of  our 
system.  Like  Venus  of  the  limpid  rays,  like  the  daz- 
zling Jupiter,  like  all  the  planets,  she  courses  through 
space,  carrying  into  Infinitude  our  hopes  and  destinies. 
Bigger  than  Mercury,  Venus,  and  Mars,  she  presents  a 
very  modest  figure  in  comparison  with  the  enormous 
Jupiter,  the  strange  system  of  Saturn,  of  Uranus,  and 
even  of  Neptune.  For  us  her  greatest  interest  is  that 
15  211 


ASTRONOMY  FOR  AMATEURS 

she  serves  as  our  residence,  and  if  she  were  not  our  habi- 
tation we  should  scarcely  notice  her.  Dark  in  herself, 
she  burns  at  a  distance  like  a  star,  returning  to  space  the 
light  she  receives  from  the  Sun.  At  the  distance  of  our 
satellite,  she  shines  like  an  enormous  moon,  fourteen 
times  larger  and  more  luminous  than  our  gentle  Phoebe. 
Observed  from  Mercury  or  Venus,  she  embellishes  the 
midnight  sky  with  her  sparkling  purity  as  Jupiter  does 
for  us.  Seen  from  Mars,  she  is  a  brilliant  morning  and 
evening  star,  presenting  phases  similar  to  those  which 
Mars  and  Venus  show  from  here.  From  Jupiter,  the 
terrestrial  globe  is  little  more  than  an  insignificant  point, 
nearly  always  swallowed  up  in  the  solar  rays.  As  to  the 
Saturnians,  Uranians,  and  Neptunians,  if  such  people 
exist,  they  probably  ignore  our  existence  altogether. 
And  in  all  likelihood  it  is  the  same  for  the  rest  of  the 
universe. 

We  must  cherish  no  illusions  as  to  the  importance 
of  our  natal  world.  It  is  true  that  the  Earth  is  not 
wanting  in  charm,  with  its  verdant  plains  enameled  in 
the  delicious  tones  of  a  robust  and  varied  vegetation,  its 
plants  and  flowers,  its  spring-time  and  its  birds,  its  lim- 
pid rivers  winding  through  the  meadows,  its  mountains 
covered  with  forests,  its  vast  and  profound  seas  ani- 
mated with  an  infinite  variety  of  living  creatures.  The 
spectacle  of  Nature  is  magnificent,  superb,  admirable 

212 


THE  EARTH 

and  marvelous,  and  we  imagine  that  this  Earth  fills  the 
universe,  and  suffices  for  it.  The  Sun,  the  Moon,  the 
stars,  the  boundless  Heavens,  seem  to  have  been  created 
for  us,  to  charm  our  eyes  and  thoughts,  to  illumine  our 
days,  and  shed  a  gentle  radiance  upon  our  nights.  This 
is  an  agreeable  illusion  of  our  senses.  If  our  Humanity 
were  extinguished,  the  other  worlds  of  the  Heavens, 
Venus,  Mars,  etc.,  would  none  the  less  continue  to  gravi- 
tate in  the  Heavens  along  with  our  defunct  planet,  and 
the  close  of  human  life  (for  which  everything  seems  to  us 
to  have  been  created)  would  not  even  be  perceived  by 
those  other  worlds,  that  nevertheless  are  our  neighbors. 
There  would  be  no  revolution,  no  cataclysm.  The 
stars  would  go  on  shining  in  the  firmament,  just  as  they 
do  to-day,  shedding  their  divine  light  over  the  immensity 
of  the  Heavens.  Nothing  would  be  changed  in  the 
general  aspect  of  the  Universe.  The  Earth  is  only  a 
modest  atom,  lost  in  the  innumerable  army  of  the  worlds 
and  suns  that  people  the  universe. 

Every  morning  the  Sun  rises  in  the  East,  setting  fire 
with  his  ardent  rays  to  the  sky,  which  is  dazzling  with 
his  splendor.  He  ascends  through  space,  reaches  a  cul- 
minating point  at  noon,  and  then  descends  toward  the 
West,  to  sink  at  night  into  the  purple  of  the  sunset. 

And  then  the  stars,  grand  lighthouses  of  the  Heavens, 
213 


ASTRONOMY  FOR  AMATEURS 

in  their  turn  incandesce.  They  too  rise  in  the  East, 
ascend  the  vault  of  Heaven,  and  then  descend  to  the 
West,  and  vanish.  All  the  orbs,  Sun,  Moon,  planets, 
stars,  appear  to  revolve  round  us  in  twenty-four 
hours. 

This  journey  of  the  orbs  around  us  is  only  an  illu- 
sion of  the  senses. 

Whether  the  Earth  be  at  rest,  and  the  sky  animated 
with  a  rotary  movement  round  her,  or  whether,  on  the 
contrary,  the  stars  are  fixed,  and  the  Earth  in  motion, 
in  either  case,  for  us  appearances  are  the  same.  If  the 
Earth  turns,  carrying  all  that  pertains  to  it  in  its  motion 
• — the  seas,  the  atmosphere,  the  clouds,  and  ourselves, — 
we  are  unable  to  perceive  it,  because  all  the  objects  that 
surround  us  keep  their  respective  positions  among  them- 
selves. Hence  we  must  resort  to  logic,  and  reason  out 
the  two  hypotheses. 

For  the  accomplishment  of  this  rapid  journey  of  the 
Sun  and  stars  around  the  Earth,  it  would  be  necessary 
that  all  the  orbs  of  the  sky  should  be  in  some  way  at- 
tached to  a  vault,  or  to  circles,  as  was  formerly  supposed. 
This  conception  is  childish.  The  peoples  of  antiquity 
had  no  notion  of  the  size  of  the  universe,  and  their  error 
is  almost  excusable.  The  distance  separating  Heaven 
from  the  Infernal  Regions  has  been  measured,  according 
to  Hesiod,  by  Vulcan's  anvil,  which  fell  from  the  skies 

214 


THE  EARTH 

to  the  Earth  in  nine  days  and  nine  nights,  and  it  would 
have  taken  as  long  again  to  continue  its  journey  from 
the  surface  of  the  Earth  to  the  bowels  of  Hades. 

To-day  we  have  a  more  exact  notion  of  the  grandeur 
of  the  Universe.  We  know  that  millions  and  trillions  of 
miles  separate  the  stars  from  one  another.  And  by 
representing  these  distances,  we  can  form  some  idea  of 
the  difficulty  there  would  be  in  admitting  the  rotation 
of  the  universe  round  the  Earth. 

The  distance  from  here  to  the  Sun  is  149,000,000 
kilometers  (93,000,000  miles).  In  order  to  turn  in 
twenty-four  hours  round  the  Earth,  that  orb  would  have 
to  fly  through  Space  at  a  velocity  of  more  than  10,000 
kilometers  (6,200  miles)  a  second. 

Yes!  the  Sun,  splendid  orb,  source  of  our  existence 
and  of  that  of  all  the  planets,  a  colossal  globe,  over  a 
million  times  more  voluminous  than  the  Earth,  and 
324  thousand  times  heavier,  would  have  to  accomplish 
this  immense  revolution  in  order  to  turn  round  the 
minute  point  that  is  our  lilliputian  world! 

This  in  itself  would  suffice  to  convince  us  of  the  want 
of  logic  in  such  an  argument.  But  the  Sun  is  not  alone 
in  the  Heavens.  We  should  have  to  suppose  that  all 
the  planets  and  all  the  stars  were  engaged  in  the  same 
fantastic  motions. 

Jupiter  is  about  five  times  as  far  off  as  the  Sun;  his 
215 


ASTRONOMY  FOR  AMATEURS 

velocity  would  have  to  be  53,000  kilometers  (32,860 
miles)  per  second. 

Neptune,  thirty  times  farther  off,  would  have  to 
execute  320,000  kilometers  (198,000  miles)  per  second. 

The  nearest  star,  a  of  the  Centaur,  situated  at  a 
distance  275,000  times  that  of  the  Sun,  would  have  to 
run,  to  fly  through  space,  at  a  rate  of  2,941,000,000 
kilometers  (1,823,420,000  miles)  per  second. 

All  the  other  stars  are  incomparably  farther  off,  at 
infinity. 

And  this  fantastic  rotation  would  all  be  accom- 
plished round  a  minute  point! 

To  put  the  problem  in  this  way  is  to  solve  it.  Unless 
we  deny  the  astronomic  measures,  and  the  most  convin- 
cing geometric  operations,  the  Earth's  diurnal  motion 
of  rotation  is  a  certainty. 

To  suppose  that  the  stars  revolve  round  the  Earth 
is  to  suppose,  as  one  author  humorously  suggests,  that 
in  order  to  roast  a  pheasant  the  chimney,  the  kitchen, 
the  house,  and  all  the  countryside  must  needs  turn 
round  it. 

If  the  Earth  turns  in  twenty-four  hours  upon  itself, 
a  point  upon  the  equator  would  simply  travel  at  a  rate  of 
465  meters  (1,525  feet)  per  second.  This  speed,  while 
considerable  in  comparison  with  the  movements  observed 
upon  the  surface  of  our  planet,  is  as  nothing  compared 

2l6 


THE  EARTH 

with  the  fantastic  rapidity  at  which  the  Sun  and  stars 
would  have  to  move,  in  order  to  rotate  round  our  globe. 

Thus  we  have  to  choose  between  these  two  hypo- 
theses: either  to  make  the  entire  Heavens  turn  round  us 
in  twenty-four  hours,  or  to  suppose  our  globe  to  be  ani- 
mated by  a  motion  of  rotation  upon  itself.  For  us,  the 
impression  is  the  same,  and  as  we  are  insensible  to  the 
motion  of  the  Earth,  its  immobility  would  seem  almost 
natural  to  us.  So  that,  in  last  resort,  here  as  in  many 
other  instances,  the  decision  must  be  made  by  simple 
common  sense.  Science  long  ago  made  its  choice. 
Moreover,  all  the  progress  of  Astronomy  has  confirmed 
the  rotary  movement  of  the  Earth  in  twenty-four  hours, 
and  its  movement  of  revolution  round  the  Sun  in  a  year; 
while  at  the  same  time  a  great  number  of  other  mo- 
tions have  been  discovered  for  our  wandering  planet. 

The  learned  philosophers  of  antiquity  divined  the 
double  movement  of  our  planet.  The  disciples  of  Py- 
thagoras taught  it  more  than  two  thousand  years  ago, 
and  the  ancient  authors  quote  among  others  Nicetas  of 
Syracuse,  and  Aristarchus  of  Samos,  as  being  among  the 
first  to  promote  the  doctrine  of  the  Earth's  movement. 
But  at  that  remote  period  no  one  had  any  idea  of  the 
real  distances  of  the  stars,  and  the  argument  did  not 
seem  to  be  based  on  any  adequate  evidence.  Ptolemy, 
after  a  long  discussion  of  the  diurnal  motion  of  our 

217 


ASTRONOMY  FOR  AMATEURS 

planet,  refutes  it,  giving  as  his  principal  reason  that 
if  the  Earth  turned,  the  objects  that  were  not  fixed  to  its 
surface  would  appear  to  move  in  a  contrary  direction, 
and  that  a  body  shot  into  the  air  would  fall  back  to  the 
West  of  its  starting-point,  the  Earth  having  turned  mean- 
time from  West  to  East.  This  objection  has  no  weight, 
because  the  Earth  controls  not  only  all  the  objects  fixed 
to  the  soil,  but  also  the  atmosphere,  and  the  clouds  that 
surround  it  like  a  light  veil,  and  all  that  exists  upon  its 
surface.  The  atmosphere,  the  clouds,  the  waters  of  the 
ocean,  things  and  beings,  all  are  adherent  to  it  and  make 
one  body  with  it,  participating  in  its  movement,  as 
sometimes  happens  to  ourselves  in  the  compartment  of  a 
train,  or  the  car  of  an  aerostat.  When,  for  instance,  we 
drop  an  object  out  of  such  a  car,  this  object,  animated 
with  the  acquired  velocity,  does  not  fall  to  a  point  below 
the  aerostat,  but  follows  the  balloon,  as  though  it  were 
gliding  along  a  thread.  The  author  has  made  this  ex- 
periment more  than  once  in  aerial  journeys. 

Thus,  the  hypothesis  of  the  Earth's  motion  has  be- 
come a  certainty.  But  in  addition  to  reasoning,  direct 
proof  is  not  wanting. 

I.  The  spheroidal  shape  of  the  Earth,  slightly  flat- 
tened at  the  poles  and  swollen  at  the  equator,  has  been 
produced  by  the  rotary  motion,  by  the  centrifugal  force 
that  it  engenders, 

218 


THE  EARTH 

2.  In  virtue  of  this  centrifugal  force,  which  is  at  its 
maximum  at  the  equator,  objects  lose  a  little  of  their 
weight  in  proportion  as  they  are  farther  removed  from 
the  polar  regions  where  centrifugal  force  is  almost  nil. 

3.  In  virtue  of  this  same  centrifugal  force,  the  length 
of  the  pendulum  in  seconds  is  shorter  at  the  equator  than 
in  Paris,  and  the  difference  is  one  of  3  millimeters. 

4.  A  weight  abandoned  to  itself  and  falling  from  a 
certain  height,  should  follow  the  vertical  if  the  Earth 
were     motionless.     Experiment,     frequently     repeated, 
shows  a  slight  deviation  to  the  East,  of  the  plumb-line 
that  marks  the  vertical.     We  more  especially   observed 
this  at  the  Pantheon  during  the  recent  experiments. 

5.  The   magnificent  experiment  of  Foucault  at  the 
Pantheon,  just  renewed  under  the   auspices   of  the  As- 
tronomical Society  of  France,  demonstrates  the  rotary 
motion   of  the   Earth  to   all    beholders.      A  sufficiently 
heavy  ball  (28  kilograms,  about  60  pounds)  is  suspended 
from  the  dome  of  the  edifice  by  an  excessively  fine  steel 
thread.     When  the  pendulum  is  in  motion,  a  point  at- 
tached to    the   bottom   of  the    ball    marks   its   passage 
upon   two    little   heaps   of  sand   arranged   some   yards 
away  from  the  center.      At  each  oscillation  this  point 
cuts  the  sand,  and  the  furrow  gets  gradually  longer  to 
the  right  hand  of  an  observer  placed  at  the  center  of 
the  pendulum.     The  plane  of  the  oscillations  remains 

219 


ASTRONOMY  FOR  AMATEURS 

fixed,  but  the  Earth  revolves  beneath,  from  West  to 
East.  The  fundamental  principle  of  this  experiment  is 
that  the  plane  in  which  any  pendulum  is  made  to  oscil- 
late remains  invariable  even  when  the  point  of  suspen- 
sion is  turned.  This  demonstration  enables  us  in  some 
measure  to  see  the  Earth  turning  under  our  feet. 

The  annual  displacements  of  the  stars  are  again  con- 
firmatory of  the  Earth's  motion  round  the  Sun.  During 
the  course  of  the  year,  the  stars  that  are  least  remote 
from  our  solar  province  appear  to  describe  minute 
ellipses,  in  perspective,  in  the  Heavens.  These  small 
apparent  variations  in  the  position  of  the  nearest  stars 
reproduce  the  annual  rotation  of  the  Earth  round  the 
Sun,  in  perspective. 

We  could  adduce  further  observations  in  favor  of 
this  double  movement,  but  the  proofs  just  given  are 
sufficiently  convincing  to  leave  no  doubt  in  the  mind  of 
the  reader. 

Nor  are  these  two  the  only  motions  by  which  our 
globe  is  rocked  in  space.  To  its  diurnal  rotation  and 
its  annual  rotation  we  may  add  another  series  of  ten 
more  motions:  some  very  slow,  fulfilling  themselves  in 
thousands  of  years,  others,  more  rapid,  being  constantly 
renewed.  It  is,  however,  impossible  in  these  restricted 
pages  to  enter  into  the  detail  reserved  for  more  complete 
works.  We  must  not  forget  that  our  present  aim  is  to 

220 


THE  EARTH 

sum  up  the  essentials  of  astronomical  knowledge  as 
simply  as  possible,  and  to  offer  our  readers  only  the 
"best  of  the  picking." 

The  two  principal  motions  of  which  we  have  just 
spoken  give  us  the  measure  of  time,  the  day  of  twenty- 
four  hours,  and  the  year  of  365!  days. 

The  Earth  turning  upon  itself  in  twenty-four  hours 
from  West  to  East,  presents  all  its  parts  in  succession  to 
the  Sun  fixed  in  space.  Illuminated  countries  have  the 
day,  those  opposite,  in  the  shadow  of  the  Earth,  are 
plunged  into  night.  The  countries  carried  by  the  Earth 
toward  the  Sun  have  morning,  those  borne  toward  his 
shadow,  evening.  Those  which  receive  the  rays  of  the 
day-star  directly  have  noon;  those  which  are  just  op- 
posite have  midnight. 

The  rotation  of  our  planet  in  this  way  gives  us  the 
measure  of  time;  it  has  been  divided  arbitrarily  into 
twenty-four  periods  called  hours;  each  hour  into  sixty 
minutes;  each  minute  into  sixty  seconds. 

In  consequence,  each  country  turns  in  twenty-four 
hours  round  the  axis  of  the  Earth.  The  difference  in 
hours  between  the  different  regions  of  the  globe  is  there- 
fore regulated  by  the  difference  of  geographical  position. 
The  countries  situated  to  the  West  are  behind  us;  the 
Sun  only  gets  there  after  it  has  shone  upon  our  meridian. 

221 


ASTRONOMY  FOR  AMATEURS 

When  it  is  midday  in  Paris,  it  is  only  11.51  A.  M.  in 
London;   11.36  A.  M.  in  Madrid;  11.14  A«  M-  at  Lisbon; 


FIG.  60. — Motion  of  the  Earth  round  the  Sun. 

11.12  A.M.  at  Mogador;  7.06  A.  M.  at  Quebec;  6.55  A.  M. 

at  New  York;  5.14  A.  M.  in  Mexico;  and  so  on.     The 

ountries  situated  to  the  East  are,  on  the  contrary,  ahead 

222 


THE  EARTH 

of  us.  When  it  is  noon  in  Paris,  it  is  already  56 
minutes  after  midday  at  Vienna;  1.25  P.  M.  at  Athens; 
2.21  P.  M.  at  Moscow;  3.16  P.M.  at  Teheran;  4.42  P.  M. 
at  Bombay;  and  so  on.  We  are  here  speaking  of  real 
times,  and  not  of  the  conventional  times. 

If  we  could  make  the  tour  of  the  world  in  twenty-four 
hours,  starting  at  midday  from  some  place  to  go  round 
the  globe,  and  traveling  westward  with  the  Sun,  we 
should  have  him  always  over  our  heads.  In  traveling 
round  the  world  from  West  to  East,  one  goes  in  front  of 
the  Sun,  and  gains  by  one  day;  in  taking  the  opposite 
direction,  from  East  to  West,  one  loses  a  day. 

In  reality,  the  exact  duration  of  the  Earth's  diurnal 
rotation  is  twenty-three  hours,  fifty-six  minutes,  four  sec- 
onds. That  is  the  sidereal  day.  But,  while  turning  upon 
itself,  the  Earth  circulates  upon  its  orbit,  and  at  the 
end  of  a  diurnal  rotation  it  is  still  obliged  to  turn  during 
three  minutes,  fifty-six  seconds  in  order  to  present  ex- 
actly the  same  meridian  to  the  fixed  Sun  which,  in  con- 
sequence of  the  rotary  period  of  our  planet,  is  a  little 
behind.  The  solar  day  is  thus  one  of  twenty-four  hours. 
There  are  366  rotations  in  the  year. 

And  now  let  us  come  back  to  the  consequences  of 
the  Earth's  motion.  In  the  first  place  our  planet  does 
not  turn  vertically  nor  on  its  side,  but  is  tipped  or  in- 
clined a  certain  quantity:  23°  27'.  « 

223 


ASTRONOMY  FOR  AMATEURS 

Now,  throughout  its  annual  journey  round  the  Sun, 
the  inclination  remains  the  same.  That  is  what  pro- 
duces the  seasons  and  climates.  The  countries  which 
have  a  larger  circle  to  travel  over  in  the  hemisphere  of 
the  solar  illumination  have  the  longer  days,  those  which 
have  a  smaller  circle,  shorter  days.  At  the  equator 
there  is  constantly,  and  all  through  the  year,  a  twelve- 
hour  day,  and  a  night  of  twelve  hours. 


FIG.  61. — Inclination  of  the  Earth. 

In  summer,  the  pole  dips  toward  the  Sun,  and  the 
rays  of  the  orb  of  day  cover  the  corresponding  hemi- 
sphere with  their  light.  Six  months  later  this  same 
hemisphere  is  in  winter,  and  the  opposite  hemisphere 
is  in  its  turn  presented  to  the  Sun.  June  21  is  the 
summer  solstice  for  the  northern  hemisphere,  and  is  at 
the  same  time  winter  for  the  southern  pole.  Six  months 
later,  on  December  21,  we  have  winter,  while  the  south- 

224 


THE  EARTH 

ern  hemisphere  is  completely  exposed  to  the  Sun.  Be- 
tween these  two  epochs,  when  the  radiant  orb  shines 
exactly  upon  the  equator,  that  is  on  March  21,  we 
have  the  spring  equinox,  that  delicious  flowering  season 
when  all  nature  is  enchanting  and  enchanted;  on  Sep- 
tember 21  we  have  the  autumn  equinox,  melancholy, 
but  not  devoid  of  charm. 

The  terrestrial  sphere  has  been  divided  into  different 
zones,  with  which  the  different  climates  are  in  relation: 

1.  The  tropical  zone,  which    extends  23°  27'  from 
one  part  to  the  other  of  the  equator.     This  is  the  hottest 
region.     It  is  limited  by  the  circle  of  the  tropics. 

2.  The  temperate  zones,  which  extend  from   23°  27' 
to  66°  23'  of  latitude,  and  where  the  Sun  sets  every  day. 

3.  The.  glacial   zones,    drawn    round   the    poles,   at 
66°  33'  latitude,  where  the  Sun  remains  constantly  above 
or  below  the  horizon  for  several  days,  or  even  several 
months.     These  glacial  zones  are  limited    by  the  polar 
circles. 

We  must  add  that  the  axis  of  the  Earth  is  a  straight 
line  that  is  supposed  to  pass  through  the  center  of  the 
globe  and  come  out  at  two  diametrically  opposite  points 
called  the  poles.  The  diurnal  rotation  of  the  Earth  is 
effected  round  this  axis. 

The  name  equator  is  given  to  a  great  circle  situated 
between  the  two  poles,  at  equal  distance,  which  divides 

225 


ASTRONOMY  FOR  AMATEURS 


the  globe  into  two  hemispheres.  The  equator  is 
divided  into  360  parts  or  degrees,  by  other  circles  that 
go  from  one  pole  to  the  other.  These  are  the  longitudes 
or  meridians  (see  Fig.  62).  The  distance  between  the 
equator  and  the  pole  is  divided  into  larger  or  smaller 
circles,  which  have  received  the  name  of  latitudes. 

90  degrees  are  reck- 
oned on  the  one  side 
and  the  other  of  the 
equator,  in  the  di- 
rection of  the  North 
and  South  poles, 
respectively.  The 
longitudes  are  reck- 
oned from  some 
point  either  to  East 
or  West:  the  lati- 
tudes are  reckoned 
North  and  South, 
from  the  equator. 

In  going  from  East  to  West,  or  inversely,  the  longitude 
changes,  but  in  passing  from  north  to  South  of  any 
spot,  it  is  the  latitude  that  alters. 

The  circles  of  latitude  are  smaller  in  proportion  as 
one  approaches  the  poles.  The  circumference  of  the 
world  is  40,076,600  meters  at  the  equator.  At  the 

226 


FIG.  62. — The  divisions  of  the  globe. 
Longitudes  and  latitudes. 


THE  EARTH 

latitude  of  Paris  (48°  50')  it  is  only  26,431,900  meters. 
A  point  situated  at  the  equator  has  more  ground  to 
travel  over  in  order  to  accomplish  its  rotation  in  twenty- 
four  hours  than  a  point  nearer  the  pole. 

We  have  already  stated  that  this  velocity  of  rotation 
is  465  meters  per  second  at  the  equator.  At  the  latitude 
of  Paris  it  is  not  more  than  305  meters.  At  the  poles 
it  is  nil. 

The  longitudes,  or  meridians,  are  great  circles  of 
equal  length,  dividing  the  Earth  into  quarters,  like  the 
parts  of  an  orange  or  a  melon.  These  circumvent  the 
globe,  and  measure  some  40,000,000  (40,008,032)  meters. 
We  may  remember  in  passing  that  the  length  of  the 
meter  has  been  determined  as,  by  definition,  the  ten- 
millionth  part  of  the  quarter  of  a  celestial  meridian. 

Thus,  while  rotating  upon  itself,  the  Earth  spins 
round  the  Sun,  along  a  vast  orbit  traced  at  149,000,000 
kilometers  (93,000,000  miles)  from  the  central  focus,  a 
sensibly  elliptical  orbit,  as  we  have  already  pointed  out. 
It  is  a  little  nearer  the  Sun  on  January  1st  than  on  July 
1st,  at  its  perihelion  (peri,  near,  belios,  Sun),  than  at 
its  aphelion  (apo,  far,  helios,  Sun).  The  difference  = 
6,000,000  kilometers  (3,720,000  miles),  and  its  velocity 
is  a  little  greater  at  perihelion  than  at  aphelion. 

This  second  motion  produces  the  year.  It  is  accom- 
plished in  three  hundred  and  sixty-five  days,  six  hours, 
16  227 


ASTRONOMY  FOR  AMATEURS 

nine  minutes,  nine  seconds.  Such  is  the  complete 
revolution  of  our  planet  round  the  orb  of  day.  It  has 
received  the  name  of  sidereal  year.  But  this  is  not  how 
we  calculate  the  year  in  practical  life.  The  civil  year, 
known  also  as  the  tropical  year,  is  not  equivalent  to 
the  Earth's  revolution,  because  a  very  slow  gyratory 
motion,  called  "the  precession  of  the  equinoxes," 
the  cycle  of  which  occupies  25,765  years,  drags  the 
spring  equinox  back  some  twenty  minutes  in  each 
year. 

The  civil  year  is,  accordingly,  three  hundred  and 
sixty-five  days,  five  hours,  forty-eight  minutes,  forty-six 
seconds. 

In  order  to  simplify  the  calendar,  this  accumulating 
fraction  of  five  hours,  forty-eight  minutes,  forty-six 
seconds  (about  a  quarter  day)  is  added  every  four  years 
to  a  bissextile  year  (leap-year),  and  thus  we  have  uneven 
years  of  three  hundred  and  sixty-five,  and  three  hundred 
and  sixty-six  days.  Every  year  of  which  the  figure  is 
divisible  by  four  is  a  leap-year.  By  adding  a  quarter  day 
to  each  year,  there  is  a  surplus  of  eleven  minutes,  fourteen 
seconds.  These  are  subtracted  every  hundred  years  by 
not  taking  as  bissextile  those  secular  years  of  which  the 
radical  is  not  divisible  by  four.  The  year  1600  was  leap- 
year:  1700, 1800,  and  1900  were  not;  2000  will  be.  The 
agreement  between  the  calendar  and  nature  has  thus 

228 


THE  EARTH 

been  fairly  perfect,  since  the  establishment  of  the  Gre- 
gorian Calendar  in  1582. 

Since  the  terrestrial  orbit  measures  not  less  than 
930,000,000  kilometers  (576,600,000  miles),  which  must 
be  traversed  in  a  year,  the  Earth  flies  through  Space  at 
2,544,000  kilometers  (1,577,280  miles)  a  day,  or  106,000 
kilometers  (65,720  miles)  an  hour,  or  29,500  meters 
(18  miles)  per  second  on  an  average,  a  little  faster  at 
perihelion,  a  little  slower  at  aphelion.  This  giddy 
course,  a  thousand  times  more  rapid  than  the  speed  of 
an  express-train,  is  effected  without  commotion,  shock, 
or  noise.  Reasoning  alone  enables  us  to  divine  the 
prodigious  movement  that  carries  us  along  in  the  vast 
fields  of  the  Infinite,  in  mid-heaven. 

Returning  to  the  calendar,  it  must  be  remarked  in 
conclusion,  that  the  human  race  has  not  exhibited  great 
sense  in  fixing  the  New  Year  on  January  I .  No  more  dis- 
agreeable season  could  have  been  selected.  And  further, 
as  the  ancient  Roman  names  of  the  months  have  been 
preserved,  which  in  the  time  of  Romulus  began  with 
March,  the  "seventh"  month,  "September,"  is  our 
ninth  month;  October  (the  eighth)  is  the  tenth;  Novem- 
ber (the  ninth)  has  become  the  eleventh;  and  December 
(the  tenth)  has  taken  the  place  of  the  twelfth.  Verily, 
we  are  not  hard  to  please! 

These  months,  again,  are  unequal,  as  every  one 
229 


ASTRONOMY  FOR  AMATEURS 


knows.  Witness  the  simple  expedient  of  remembering 
the  long  and  short  months,  by  closing  the  left  hand  and 
counting  the  knobs  and  hollows  of  the  fist,  the  former 
corresponding  to  the  long  months,  the  latter  to  the  short: 


JANUARY        31   Days 
FEBRUARY  28«*29  •• 
31      " 

30  •• 

31  " 


MARCH 
APRIL 
r  MAY 
JUNE 
lJULV 


3O 
31 


AUGUST  31  •* 

SEPTEMBER  30  - 

OCTOBER  31  ~ 
NOVEMBER  30  - 

DECEMBER    31    * 


FIG.  63. — To  find  the 
long  and  short  months. 


first  knob  =  January;    first  hollow,  February;    second 
knob,  March;  and  so  on.* 

*  Translator  :   Compare  the  well-known  English  rhyme : 
Thirty  days  hath  September, 
April,  June,  and  November. 
While  all  the  rest  have  thirty-one, 
Excepting  February  alone, 
In  which  but  twenty-eight  appear 
And  twenty-nine  when  comes  Leap  Year 

230 


THE  EARTH 

Should  not  the  real  renewal  of  the  year  coincide  with 
the  awakening  of  Nature,  with  the  spring  on  the  terres- 
trial hemisphere  occupied  by  the  greater  portion  of  Hu- 
manity, with  the  date  of  March  2ist?  Should  not  the 
months  be  equalized,  and  their  names  modified  ?  Why 
should  we  not  follow  the  beautiful  evolution  dictated 
by  the  Sun  and  by  the  movement  of  our  planet  ?  But 
our  poor  Earth  may  roll  on  a  long  time  yet  before  its 
inhabitants  will  become  reasonable. 


231 


CHAPTER  IX 
THE   MOON 

IT  is  the  delightful  hour  when  all  Nature  pauses  in 
the  tranquil  calm  of  the  silent  night. 

The  Sun  has  cast  his  farewell  gleams  upon  the  weary 
Earth.  All  sound  is  hushed.  And  soon  the  stars  will 
shine  out  one  by  one  in  the  bosom  of  the  somber  firma- 
ment. Opposite  to  the  sunset,  in  the  east,  the  Full 
Moon  rises  slowly,  as  it  were  calling  our  thoughts  toward 
the  mysteries  of  eternity,  while  her  limpid  night  spreads 
over  space  like  a  dew  from  Heaven. 

In  the  odorous  woods,  the  trees  are  silhouetted 
strangely  upon  the  sky,  seeming  to  stretch  their  knotted 
arms  toward  this  celestial  beauty.  On  the  river,  smooth 
as  a  mirror,  wherein  the  pale  Phoebe  reflects  her  splen- 
dor, the  maidens  go  to  seek  the  floating  image  of  their 
future  spouse.  And  in  response  to  their  prayers,  she 
rends  the  veil  of  cloud  that  hides  her  from  their  eyes, 
and  pours  the  reflection  of  her  gentle  beams  upon  the 
sleeping  waters. 

From  all  time  the  Moon  has  had  the  privilege  of 
232 


THE  MOON 

charming  the  gaze,  and  attracting  the  particular  attention 
of  mortals.  What  thoughts  have  not  been  wafted  to  her 
pale,  yet  luminous  disk  ?  Orb  of  mystery  and  of  soli- 
tude, brooding  over  our  silent  nights,  this  celestial  lumi- 
nary is  at  once  sad  and  splendid  in  her  glacial  purity, 
and  her  limpid  rays  provoke  a  reverie  full  of  charm 
and  melancholy.  Mute  witness  of  terrestrial  destinies, 
her  nocturnal  flame  watches  over  our  planet,  following 
it  in  its  course  as  a  faithful  satellite. 

The  human  eye  first  uplifted  to  the  Heavens  was 
struck,  above  all,  with  the  brilliancy  of  this  solitary  globe, 
straying  among  the  stars.  The  Moon  first  suggested 
an  easy  division  of  time  into  months  and  weeks,  and 
the  first  astronomical  observations  were  limited  to  the 
study  of  her  phases. 

Daughter  of  the  Earth,  the  Moon  was  born  at  the 
limits  of  the  terrestrial  nebula,  when  our  world  was  still 
no  more  than  a  vast  gaseous  sphere,  and  was  detached 
from  her  at  some  critical  period  of  colossal  solar  tide. 
Separating  with  regret  from  her  cradle,  but  attached  to 
the  Earth  by  indissoluble  ties  of  attraction,  she  rotates 
round  us  in  a  month,  from  west  to  east,  and  this  move- 
ment keeps  her  back  a  little  each  day  in  relation  to  the 
stars.  If  we  watch,  evening  by  evening,  beginning  from 
the  new  moon,  we  shall  observe  that  she  is  each  night 
a  little  farther  to  the  left,  or  east,  than  on  the  preceding 

233 


ASTRONOMY  FOR  AMATEURS 

evening.  This  revolution  of  the  Moon  around  our 
planet  produces  the  phases,  and  gives  the  measure  of 
our  months. 


FIG.  64. — The  Full  Moon  slowly  rises, 
234 


THE  MOON 

During  her  monthly  journey  she  always  presents 
the  same  face  to  us.  One  might  think  that  the  fear  of 
losing  us  had  immobilized  her  globe,  and  prevented  her 
from  turning.  And  so  we  only  know  of  her  the  vague 
sketch  of  a  human  face  that  has  been  observed  through 
all  the  ages. 

It  seems,  in  fact,  as  though  she  were  looking  down 
upon  us  from  the  Heavens,  the  more  so  as  the  principal 
spots  of  her  disk  vaguely  recall  the  aspect  of  a  face.  If 
we  try  to  draw  it  without  the  aid  of  instruments  we 
observe  dark  regions  and  clear  regions  that  each  inter- 
prets in  his  own  fashion.  To  the  author,  for  instance, 
the  full  Moon  has  the  appearance  represented  in  the 
following  figure.  The  spots  resemble  two  eyes  and  the 
sketch  of  a  nose;  resulting  in  a  vague  human  figure, 
as  indicated  on  the  lower  disk.  Others  see  a  man  car- 
rying a  bundle  of  wood,  a  hare,  a  lion,  a  dog,  a  kan- 
garoo, a  sickle,  two  heads  embracing,  etc.*  But  gen- 
erally speaking,  there  is  a  tendency  to  see  a  human 
figure  in  it. 

If  this  appearance  is  helped  a  little  by  drawing,  it 
gives  the  profile  of  a  man's  head  fairly  well  sketched, 
and  furnished  with  an  abundant  crop  of  hair  (Fig.  66). 

*  Fifty-eight  different  pictures  of  the  aspect  of  the  Moon  to  the  unaided 
eye  will  be  found  in  the  Monthly  Bulletins  of  the  Astronomical  Society  of 
France,  for  the  year  1900,  in  pursuance  of  an  investigation  made  by  the 
author  among  the  different  members  of  the  Society. 

235 


ASTRONOMY  FOR  AMATEURS 

Others  go  much  more  into  detail,  and  draw  a  woman's 
head  that  is  certainly  too  definite,  like  this  of  M.  Jean 


FIG.  69.— The  Moon  viewed  with  the  unaided  eye. 

Sardou   (Fig.   67).      Others,  again,   like   M.   Zamboni, 
see  behind  the  man's  profile  the  likeness  of  a  young  girl 

236 


THE  MOON 

being  embraced  by  him  (Fig.  68).  There  is  certainly 
some  imagination  about  these.  And  yet,  on  the  first 
suitable  occasion,  look  at  the  Moon  through  an  opera- 
glass,  a  few  days  after  the  first  quarter,  and  you  will 


FIG.  66. — The  Man's  head  in  the  Moon. 

not  fail  to  see  the  masculine  profile  just  described,  and 
even  to  imagine  the  "kiss  in  the  Moon." 

These  vague  aspects  disappear  as  soon  as  the  Moon 
is  examined  with  even  the  least  powerful  instruments: 

237 


ASTRONOMY  FOR  AMATEURS 

the  spots  are  better  defined,  and  the  illusions  of  indistinct 
vision  vanish.  Compare  this  direct  photograph  of  the 
Moon,  taken  by  the  author  some  years  ago  (Fig.  69): 
here  is  neither  a  human  figure,  man,  dog,  hare,  nor 
faggot;  simply  deep  geographical  configurations,  and  in 
the  lower  region,  a  luminous  point  whence  certain  light 


FIG.  67. — Woman's  head  in  the  Moon. 

bands  spread  out,  some  being  prolonged  to  a  consider- 
able , distance.  And  yet,  from  a  little  way  off,  does  it 
not  form  the  man's  face  above  indicated  ? 

From  the  earliest  astronomical  observations  made 
with  the  aid  of  instruments  by  Galileo,  in  1609,  people 
tried  to  find  out  what  the  dark  spots  could  represent, 

238 


THE  MOON 

and  they  were  called  seas,  because  water  absorbs  light, 
and  reflects  it  less  than  terra  firma.     The  Mo.on  of  itself 


FIG.  68. — The  kiss  in  the  Moon. 
239 


ASTRONOMY  FOR  AMATEURS 

possesses  no  intrinsic  light,  any  more  than  our  planet, 
and  only  shines  by  the  light  of  the  Sun  that  illuminates 
it.  As  it  rotates  round  the  Earth,  and  constantly 
changes  its  position  with  respect  to  the  Sun,  we  see  more 


FIG.  69. — Photograph  of  the  Moon. 

or  less  of  its  illuminated  hemisphere,  and  the  result  is 
the  phases  that  every  one  knows  so  well. 

At  the  commencement  of  each  lunation,  the  Moon  is 
between  the  Sun  and  the  Earth,  and  its  non-illuminated 
hemisphere  is  turned  toward  us.  This  is  the  New 

240 


THE  MOON 

Moon,  invisible  to  us;  but  two  days  later,  the  slim  cres- 
cent of  Diana  sheds  a  gentle  radiance  upon  the  Earth. 
Gradually  the  crescent  enlarges.  When  the  Moon  ar- 
rives at  right  angles  with  ourselves  and  with  the  Sun, 
half  the  illuminated  hemisphere  is  presented  to  us. 
This  is  the  first  quarter.  At  the  time  of  Full  Moon,  it  is 
opposite  the  Sun,  and  we  see  the  whole  of  the  hemisphere 

9 


FIG.  70. — The  Moon's  Phases. 


illuminated.  Then  comes  the  decline:  the  brilliant  disk 
is  slightly  corroded  at  first;  it  diminishes  from  day  to  day, 
and  about  a  week  before  the  New  Moon  our  fair  friend 
only  shows  her  profile  before  she  once  more  passes  in 
front  of  the  Sun:  this  is  the  last  quarter. 

When  the  Moon  is  crescent,  in  the  first  evenings  of 
the  lunation,  and  after  the  last  quarter,  the  rest  of  the 

241 


ASTRONOMY  FOR  AMATEURS 

disk  is  visible,  illuminated  feebly  by  a  pale  luminosity. 
This  is  known  as  the  ashy  light.  It  is  due  to  the  shine 
of  the  Earth,  reflecting  the  light  received  from  the  Sun 
into  space.  Accordingly  the  ashy  light  is  the  reflection 
of  our  own  sent  back  to  us  by  the  Moon.  It  is  the  reflec- 
tion of  a  reflection. 

This  rotation  of  the  Moon  round  the  Earth  is  accom- 
plished in  twenty-seven  days,  seven  hours,  forty-three 
minutes,  eleven  seconds;  but  as  the  Earth  is  simulta- 
neously revolving  round  the  Sun,  when  the  Moon  returns 
to  the  same  point  (the  Earth  having  become  displaced 
relatively  to  the  Sun),  the  Moon  has  to  travel  two  days 
longer  to  recover  its  position  between  the  Sun  and  the 
Earth,  so  that  the  lunar  month  is  longer  than  the  sidereal 
revolution  of  the  Moon,  and  takes  twenty-nine  days, 
twelve  hours,  forty-four  minutes,  three  seconds.  This 
is  the  duration  of  the  sequence  of  phases. 

This  revolution  is  accomplished  at  a  distance  of 
384,000  kilometers  (238,000  miles).  The  velocity  of 
the  Moon  in  its  orbit  is  more  than  I  kilometer  (0.6214 
mile)  per  second.  But  our  planet  sweeps  it  through 
space  at  a  velocity  almost  thirty  times  greater. 

The  diameter  of  the  Moon  represents  -3%%  tnat  °f 
the  Earth,  /.  <?.,  3,480  kilometers  (2,157  miles). 

Its  surface  =  38,000,000  square  kilometers 
(15,000,000  square  miles),  a  little  more  than  the  thir- 

242 


THE  MOON 

teenth  part  of  the  terrestrial  surface,  which  =  510,000,000 
(200,000,000  square  miles). 

In  volume,  the  Moon  is  fifty  times  less  than  the 
Earth.  Its  mass  or  weight  is  only  -^L-  that  of  the  ter- 
restrial globe.  Its  density  =  0.615,  relatively  to  that 
of  the  Earth,  /.  e.,  a  little  more  than  three  times  that  of 
water.  Weight  at  its  surface  is  very  little:  0.174.  A 
kilogram  transported  thither  would  only  weigh  174 
grams. 

At  the  meager  distance  of  384,000  kilometers 
(238,000  miles)  that  separates  us  from  it  (about  thirty 
times  the  diameter  of  the  Earth),  the  Moon  is  a  suburb 
of  our  terrestrial  habitation.  What  does  this  small  dis- 
tance amount  to  ?  It  is  a  mere  step  in  the  universe. 

A  telegraphic  message  would  get  there  in  one  and 
a  half  second;  a  projectile  fired  from  a  gun  would  arrive 
in  eight  days,  five  hours;  an  express-train  would  be  due 
in  eight  months,  twenty-two  days.  It  is  only  the  -g-|-g- 
part  of  the  distance  that  separates  us  from  the  Sun, 
and  only  the  yorinroT  Part  °f  tne  distance  of  the  stars 
nearest  to  us.  Many  men  have  tramped  the  distance 
that  separates  us  from  the  Moon.  A  bridge  of  thirty 
terrestrial  globes  would  suffice  to  unite  the  two  worlds. 

Owing  to  this  great  proximity,  the  Moon  is  the  best 
known  of  all  the  celestial  spheres.  Its  geographical 
17  243 


ASTRONOMY  FOR  AMATEURS 

(or  more  correctly,  selenographical,  Selene,  moon)  map 
was  drawn  out  more  than  two  centuries  ago,  at  first  in  a 
vague  sketch,  and  afterward  with  more  details,  until 
to-day  it  is  as  precise  and  accurate  as  any  of  our  ter- 
restrial maps  of  geography. 

Before  the  invention  of  the  telescope,  from  antiquity 
to  the  seventeenth  century,  people  lost  themselves  in 
conjectures  as  to  the  nature  of  this  strange  lunar  figure. 
It  was  held  to  be  a  mysterious  world,  the  more  extraor- 
dinary in  that  it  always  presented  the  same  face  to  us. 
Some  compared  it  to  an  immense  mirror  reflecting  the 
image  of  the  Earth.  Others  pictured  it  as  a  silver  star, 
an  enchanted  abode  where  all  was  wealth  and  happiness. 
For  many  a  long  day  it  was  the  fashion  to  think,  quite 
irrationally,  that  the  inhabitants  of  the  Moon  were 
fifteen  times  bigger  than  ourselves. 

The  invention  of  telescopes,  however,  brought  a 
little  order  and  a  grain  of  truth  into  these  fantastic 
assumptions.  The  first  observations  of  Galileo  revo- 
lutionized science,  and  his  discoveries  filled  the  best- 
ordered  minds  with  enthusiasm.  Thenceforward,  the 
Moon  became  our  property,  a  terrestrial  suburb,  where 
the  whole  world  would  gladly  have  installed  itself,  had 
the  means  of  getting  there  been  as  swift  as  the  wings  of 
the  imagination.  It  became  easy  enough  to  invent  a 
thousand  enchanting  descriptions  of  the  charms  of  our 

244 


THE  MOON 

fair  sister,  and  no  one  scrupled  to  do  so.  Soon,  it  was 
observed  that  the  Moon  closely  resembled  the  Earth  in 
its  geological  features;  its  surface  bristles  with  sharp 
mountain  peaks  that  light  up  in  so  many  luminous 
points  beneath  the  rays  of  the  Sun.  Alongside,  dark 
and  shaded  parts  indicate  the  plains;  moreover,  there 
are  large  gray  patches  that  were  supposed  to  be  seas 
because  they  reflect  the  solar  light  less  perfectly  than 
the  adjacent  countries.  At  that  epoch  hardly  anything 
was  known  of  the  physical  constitution  of  the  Moon, 
and  it  was  figured  as  enveloped  with  an  atmospheric 
layer,  analogous  to  that  at  the  bottom  of  which  we  carry 
on  our  respiration. 

To-day  we  know  that  these  "seas"  are  destitute  of 
water,  and  that  if  the  lunar  glebe  possesses  an  atmos- 
phere, it  must  be  excessively  light. 

The  Moon  became  the  favorite  object  of  astrono- 
mers, and  the  numerous  observations  made  of  it  author- 
ized the  delineation  of  very  interesting  selenographic 
charts.  In  order  to  find  one's  way  among  the  seas, 
plains,  and  mountains  that  make  up  the  lunar  territory, 
it  was  necessary  to  name  them.  The  seas  were  the  first 
to  be  baptized,  in  accordance  with  their  reputed  astro- 
logical influences.  Accordingly,  we  find  on  the  Moon, 
the  Sea  of  Fecundity,  the  Lake  of  Death,  the  Sea  of 
Humors,  the  Ocean  of  Tempests,  the  Sea  of  Tranquillity, 

245 


ASTRONOMY  FOR  AMATEURS 

the  Marsh  of  Mists,  the  Lake  of  Dreams,  the  Sea  of 
Putrefaction,  the  Peninsula  of  Reverie,  the  Sea  of 
Rains,  etc. 

With  regard  to  the  luminous  parts  and  the  mountains, 
it  was  at  first  proposed  to  call  them  after  the  most  illus- 
trious astronomers,  but  the  fear  of  giving  offense  acted 
as  a  check  on  Hevelius  and  Riccioli,  authors  of  the  first 
lunar  maps  (1647,  I^5I)>  anc^  they  judged  it  more 
prudent  to  transfer  the  names  of  the  terrestrial  moun- 
tains to  the  Moon.  The  Alps,  the  Apennines,  the  Pyre- 
nees, the  Carpathians,  are  all  to  be  found  up  there;  then, 
as  the  vocabulary  of  the  mountains  was  not  adequate, 
the  scientists  reasserted  their  rights,  and  we  meet  in  the 
Moon,  Aristotle,  Plato,  Hipparchus,  Ptolemy,  Coper- 
nicus, Kepler,  Newton,  as  well  as  other  more  modern 
and  even  contemporaneous  celebrities. 

We  have  not  space  to  reproduce  the  general  chart 
of  the  Moon  (that  published  by  the  author  measures  not 
less  than  a  meter,  with  the  nomenclature);  but  the  figure 
subjoined  gives  a  summary  sufficient  for  the  limits  of 
this  little  book.  Here  are  the  names  of  the  principal 
lunar  mountains,  with  the  numbers  corresponding  to 
them  upon  the  map. 

The  constantly  growing  progress  of  optics  leads  to 
perpetual  new  discoveries  in  science,  and  at  the  present 
time  we  can  say  that  we  know  the  geography  of  the  Moon 

246 


FIG.  71.  —  Map  of  the  Moon. 

(From  Fowler's  "Telescopic  Astronomy.") 

I      Furnerius 

14     Albategnius 

17     Arzachel 

*     Petavius 

1  5     Hipparchus 

28     Walter 

3     Langrenus 

1  6     Manilius 

29     Clavius 

4     Macrobius 

1  7     Eudoxus 

30     Tycho 

5      Cleomedes 

1  8     Aristotle 

3  1     Bullialdus 

6     Endymion 

1  9     Cassini 

32     Schiller 

7     Altas 

20     Aristillus 

3  3      Schickard 

8      Hercules 

21      Plato 

34     Gassendi 

9     Romer 

22     Archimedes 

35     Kepler  ^ 

10     Posidonius 

23      Eratosthenes 

36     Grimaldi 

1  1      Fracastorius 

24     Copernicus 

37     Aristarchus 

iz     Theophilus 

25      Ptolemy 

1  3     Piccolomini 

26     Alphonsus 

A    Mare  Crisum 

F    Mare  Imbrium 

V    Altai  Mountains 

B        "      Fercunditatis 

G    Sinus  Iridum 

W  Mare  Vaporum 

C        "     Nectaris 

H    Oceanus  Procellarum 

X    Apennine  Mountains 

D       "     Tranquilitatis 

I      Mare  Humorum 

Y    Caucasus         " 

E       "     Serenitatis 

K       "     Nubium 

Z   Alps 

247 


ASTRONOMY  FOR  AMATEURS 

as  well  as,  and  even  better  than,  that  of  our  own  planet. 
The  heights  of  all  the  mountains  of  the  Moon  are  meas- 
ured to  within  a  few  feet.  (One  cannot  say  as  much 
for  the  mountains  of  the  Earth.)  The  highest  are  over 
7,000  meters  (nearly  25,000  feet).  Relatively  to  its 
proportions,  the  satellite  is  much  more  mountainous 
than  the  planet,  and  the  plutonian  giants  are  much  more 
numerous  there  than  here.  If  we  have  peaks,  like 
the  Gaorisankar,  the  highest  of  the  Himalayas  and 
of  the  whole  Earth,  whose  elevation  of  8,840  meters 
(29,000  feet)  is  equivalent  to  TjVo"  the  diameter  of 
our  globe,  there  are  peaks  on  the  Moon  of  7,700 
meters  (25,264  feet),  e.g.,  those  of  Doerfel  and  Leibniz, 
the  height  of  which  is  equivalent  to  f\-ff  the  lunar  di- 
ameter. 

Tycho's  Mountain  is  one  of  the  finest  upon  our 
satellite.  It  is  visible  with  the  naked  eye  (and  perfectly 
with  opera-glasses)  as  a  white  point  shining  like  a  kind 
of  star  upon  the  lower  portion  of  the  disk.  At  the  time 
of  full  moon  it  is  dazzling,  and  projects  long  rays  from 
afar  upon  the  lunar  globe.  So,  too,  Mount  Coper- 
nicus, whose  brilliant  whiteness  sparkles  in  space.  But 
the  strangest  thing  about  these  lunar  mountains  is  that 
they  are  all  hollow,  and  can  be  measured  as  well  in  depth 
as  in  height.  A  type  of  mountain  as  strange  to  us  as 
are  the  seas  without  water!  In  effect,  these  mountains 

248 


THE  MOON 

of  the  moon  are  ancient  volcanic  craters,  with  no  sum- 
mits, nor  covers. 

At  the  top  of  the  highest  peaks,  there  is  a  large  cir- 
cular depression,  prolonged  into  the  heart  of  the  moun- 
tain, sometimes  far  below  the  level  of  the  surrounding 
plains,  and  as  these  craters  often  measure  several  hun- 
dred kilometers,  one  is  obliged,  if  one  does  not  want  to 
go  all  round  them  in  crossing  the  mountain,  to  descend 
almost  perpendicularly  into  the  depths  and  cross  there, 
to  reascend  the  opposite  side,  and  return  to  the  plain. 
These  alpine  excursions  incontestably  deserve  the  name 
of  perilous  ascents! 

No  country  on  the  Earth  can  give  us  any  notion  of 
the  state  of  the  lunar  soil:  never  was  ground  so  tor- 
mented; never  globe  so  profoundly  shattered  to  its  very 
bowels.  The  mountains  are  accumulations  of  enormous 
rocks  tumbled  one  upon  the  other,  and  round  the  awful 
labyrinth  of  craters  one  sees  nothing  but  dismantled 
ramparts,  or  columns  of  pointed  rocks  like  cathedral 
spires  issuing  from  the  chaos. 

As  we  said,  there  is  no  atmosphere,  or  at  least  so 
little  at  the  bottom  of  the  valleys  that  it  is  imperceptible. 
No  clouds,  no  fog,  no  rain  nor  snow.  The  sky  is  an 
eternally  black  space,  vaultless,  jeweled  with  stars  by 
day  as  by  night. 

Let  us  suppose  that  we  arrive  among  these  savage 
249 


ASTRONOMY  FOR  AMATEURS 

steppes  at  daybreak:  the  lunar  day  is  fifteen  times  longer 
than  our  own,  because  the  Sun  takes  a  month  to  illumi- 
nate the  entire  circuit  of  the  Moon;  there  are  no  less 
than  354  hours  from  the  rising  to  the  setting  of  the  Sun. 
If  we  arrive  before  the  sunrise,  there  is  no  aurora  to 
herald  it,  for  in  the  absence  of  atmosphere  there  can  be 
no  sort  of  twilight.  Of  a  sudden  on  the  dark  horizon 
come  flashes  of  the  solar  light,  striking  the  summits  of 
the  mountains,  while  the  plains  and  valleys  are  still  in 
darkness.  The  light  spreads  slowly,  for  while  on  the 
Earth  in  central  latitudes  the  Sun  takes  only  two  minutes 
and  a  quarter  to  rise,  on  the  Moon  it  takes  nearly  an 
hour,  and  in  consequence  the  light  it  sends  out  is  very 
weak  for  some  minutes,  and  increases  excessively 
slowly.  It  is  a  kind  of  aurora,  but  lasts  a  very  short 
time,  for  when  at  the  end  of  half  an  hour,  the  solar  disk 
has  half  risen,  the  light  appears  as  intense  to  the  eye 
as  when  it  is  entirely  above  the  horizon;  the  radiant 
orb  is  seen  with  its  protuberances  and  its  burning  at- 
mosphere. It  rises  slowly,  like  a  luminous  god,  in  the 
depths  of  the  black  sky,  a  profound  and  formless  sky 
in  which  the  stars  shine  all  day,  since  they  are  not  hidden 
by  any  atmospheric  veil  such  as  conceals  them  from  us 
during  the  daylight. 

The  absence  of  sensible  atmosphere    must  produce 
an  effect  on  the  temperature  of  the  Moon  analogous  to 

250 


THE  MOON 


that  perceived  on  the  high  mountains  of  our  globe,  where 
the  rarefaction  of  the  air  does  not  permit  the  solar  heat 


FIG.  72. — The  Lunar  Apennines. 

to  concentrate  itself  upon  the  surface  of  the  soil,  as  it 
does  below  the  atmosphere,  which  acts  as  a  forcing- 
house:  the  Sun's  heat  is  not  kept  in  by  anything,  and 

251 


ASTRONOMY  FOR  AMATEURS 

incessantly  radiates  out  toward  space.  In  all  probability 
the  cold  is  extremely  and  constantly  rigorous,  not  only 
during  the  nights,  which  are  fifteen  times  longer  than 
our  own,  but  even  during  the  long  days  of  sunshine. 

We  give  two  different  drawings  to  represent  these  cu- 
rious aspects  of  lunar  topography.  The  first  (Fig.  72) 
is  taken  in  the  neighborhood  of  the  Apennines,  and 
shows  a  long  chain  of  mountains  beneath  which  are 
three  deep  rings,  Archimedes,  Aristillus.  and  Autolycus: 
the  second  (Fig.  73)  depicts  the  lunar  ring  of  Flam- 
marion,*  whose  outline  is  constructed  of  dismantled 
ramparts,  and  whose  depths  are  sprinkled  with  little 
craters.  The  first  of  these  two  drawings  was  made 
in  England  by  Nasmyth,  the  second  in  Germany  by 
Krieger:  they  both  give  an  exact  idea  of  what  one 
sees  in  the  telescope  with  different  modes  of  solar  illu- 
mination. 

In  the  Moon's  always  black  and  starry  sky  a  majestic 
star  that  is  not  visible  from  the  Earth,  and  exhibits 
this  peculiarity  that  it  is  stationary  in  the  Heavens,  while 
all  the  others  pass  behind  it,  may  constantly  be  admired, 
by  day  as  well  as  by  night;  and  it  is  also  of  considerable 

*  My  readers  are  charged  not  to  speak  of  this  property  (which  is  fairly  ex- 
tensive), lest  the  Budget  Commission,  at  the  end  of  its  resources,  should  be 
tempted  to  put  on  an  unexpected  tax.  This  ring,  which  the  astronomers 
presented  to  me  in  the  year  1887,  is  almost  in  the  center  of  the  lunar  disk,  to 
the  north  of  Ptolemy  and  Herschel. 

252 


THE  MOON 

apparent  magnitude.  This  orb,  some  four  times  as 
large  as  the  Moon  in  diameter,  and  thirteen  to  fourteen 
times  more  extensive  in  surface,  is  our  Earth,  which 
presents  to  the  Moon  a  sequence  of  phases  similar  to 


FIG.  73. — Flammarion's  Lunar  Ring. 

those  which  our  satellite  presents  to  us,  but  in  the 
inverse  direction.  At  the  moment  of  New  Moon,  the 
Sun  fully  illuminates  the  terrestrial  hemisphere  turned 
toward  our  satellite,  and  we  get  "Full  Earth";  at  the 

253 


ASTRONOMY  FOR  AMATEURS 

time  of  Full  Moon,  on  the  contrary,  the  non-illuminated 
hemisphere  of  the  Earth  is  turned  toward  the  satellite, 
and  we  get  "New  Earth":  when  the  Moon  shows  us 
first  quarter>  the  Earth  is  in  last  quarter,  and  so  on. 
The  drawing  subjoined  gives  an  idea  of  these  aspects. 

What  a  curious  sight  our  globe  must  be  during  this 
long  night  of  fourteen  times  twenty-four  hours!     Inde- 


Frc.  74. — Lunar  landscape  with  the  Earth  in  the  sky. 

pendent  of  its  phases,  which  bring  it  from  first  quarter 
to  full  earth  for  the  middle  of  the  night,  and  from  full 
earth  to  last  quarter  for  sunrise,  how  interested  we 
should  be  to  see  it  thus  stationary  in  the  sky,  and 
turning  on  itself  in  twenty-four  hours. 

Yes,  thanks  to  us,  the  inhabitants  of  the  lunar  hemi- 
sphere turned  toward  us  are  gratified  by  the  sight  of  a 

254 


THE  MOON 

splendid  nocturnal  torch,  doubtless  less  white  than  our 
own  despite  the  clouds  with  which  the  terrestrial  globe  is 
studded,  and  shaded  in  a  tender  tone  of  bluish  emerald- 
green.  The  royal  orb  of  their  long  nights,  the  Earth, 
gives  them  moonlight  of  unparalleled  beauty,  and  we 
may  say  without  false  modesty  that  our  presence  in  the 
lunar  sky  must  produce  marvelous  and  absolutely  fairy- 
like  effects. 

Maybe,  they  envy  us  our  globe,  a  dazzling  dwelling- 
place  whose  splendor  radiates  through  space;  they  see 
its  greenish  clarity  varying  with  the  extent  of  cloud 
that  veils  its  seas  and  continents,  and  they  observe  its 
motion  of  rotation,  by  which  all  the  countries  of  our 
planet  are  revealed  in  succession  to  its  admirers. 

We  are  talking  of  these  pageants  seen  from  the  Moon, 
and  of  the  inhabitants  of  our  satellite  as  if  they  really 
existed.  The  sterile  and  desolate  aspect  of  the  lunar 
world,  however,  rather  brings  us  to  the  conclusion  that 
such  inhabitants  are  non-existent,  although  we  have 
no  authorization  for  affirming  this.  That  they  have 
existed  seems  to  me  beyond  doubt.  The  lunar  vol- 
canoes had  a  considerable  activity,  in  an  atmosphere 
that  allowed  the  white  volcanic  ashes  to  be  carried  a  long 
way  by  the  winds,  figuring  round  the  craters  the  stellar 
rays  that  are  still  so  striking.  These  cinders  were 
spread  over  the  soil,  preserving  all  its  asperities  of  outline, 

255 


ASTRONOMY  FOR  AMATEURS 

a  little  heaped  up  on  the  side  to  which  they  were  im- 
pelled. The  magnificent  photographs  recently  made  at 
the  Paris  Observatory  by  MM.  Loewy  and  Puiseux  are 
splendid  evidence  of  these  projections,  in  this  era  of 
planetary  activity  there  were  liquids  and  gases  on  the 
surface  of  the  lunar  globe,  which  appear  subsequently 
to  have  been  entirely  absorbed.  Now  the  teaching  of 
our  own  planet  is  that  Nature  nowhere  remains  infertile, 
and  that  the  production  of  Life  is  a  law  so  general  and 
so  imperious  that  life  develops  at  its  own  expense,  sooner 
than  abstain  from  developing.  Accordingly,  it  is  diffi- 
cult to  suppose  that  the  lunar  elements  can  have  re- 
mained inactive,  when  only  next  door  they  exhibited 
such  fecundity  upon  our  globe.  Yes,  the  Moon  has 
been  inhabited  by  beings  doubtless  very  different  from 
ourselves,  and  perhaps  may  still  be,  although  this  globe 
has  run  through  the  phases  of  its  astral  life  more  rapidly 
than  our  own,  and  the  daughter  is  relatively  older  than 
the  mother. 

The  duration  of  the  life  of  the  worlds  appears  to 
have  been  in  proportion  with  their  masses.  The  Moon 
cooled  and  mineralized  more  quickly  than  the  Earth. 
Jupiter  is  still  fluid. 

The  progress  of  optics  brings  us  already  very  close 
to  this  neighboring  province.  'Tis  a  pity  we  can  not 
get  a  little  nearer! 


THE  MOON 

A  telescopic  magnification  of  2,000  puts  the  Moon  at 
-  or  192  kilometers  (some  120  miles)  from  our 
eye.  Practically  we  can  obtain  no  more,  either  from 
the  most  powerful  instruments,  or  from  photographic 
enlargements.  Sometimes,  exceptionally,  enlargements 
of  3,000  can  be  used.  This  =  3 1 ft  j {f &  or  128  kilometers 
(some  80  miles).  Undoubtedly,  this  is  an  admirable 
result,  which  does  the  greatest  honor  to  human  intelli- 
gence. But  it  is  still  too  far  to  enable  us  to  determine 
anything  in  regard  to  lunar  life. 

Any  one  who  likes  to  be  impressed  by  grand  and 
magnificent  sights  may  turn  even  a  modest  field-glass 
upon  our  luminous  satellite,  at  about  first  quarter,  when 
the  relief  of  its  surface,  illuminated  obliquely  by  the  Sun, 
is  at  its  greatest  value.  If  you  examine  our  neighbor 
world  at  this  period,  for  choice  at  the  hour  of  sunset, 
you  will  be  astonished  at  its  brilliancy  and  beauty.  Its 
outlines,  its  laces,  and  embroideries,  give  the  image  of  a 
jewel  of  shining  silver,  translucent,  fluid,  palpitating  in 
the  ether.  Nothing  could  be  more  beautiful,  nothing 
purer,  and  more  celestial,  than  this  lunar  globe  floating 
in  the  silence  of  space,  and  sending  back  to  us  as  in  some 
fairy  dream  the  solar  illumination  that  floods  it.  But 
yesterday  I  received  the  same  impression,  watching  a 
great  ring  half  standing  out,  and  following  the  progress 
of  the  Sun  as  it  mounted  the  lunar  horizon  to  touch  these 

257 


ASTRONOMY  FOR  AMATEURS 

silvered  peaks.  And  I  reflected  that  it  is  indeed  incon- 
ceivable that  i%9oVoT  °f  tne  inhabitants  of  our  planet 
should  pass  their  lives  without  ever  having  attended  to 
this  pageant,  nor  to  any  of  those  others  which  the  di- 
vine Urania  scatters  so  profusely  beneath  the  wonder- 
ing gaze  of  the  observers  of  the  Heavens. 


258 


CHAPTER  X 
THE    ECLIPSES 

AMONG  all  the  celestial  phenomena  at  which  it  may 
be  our  lot  to  assist  during  our  contemplation  of  the 
universe,  one  of  the  most  magnificent  and  imposing  is 
undoubtedly  that  which  we  are  now  going  to  consider. 

The  hirsute  comets,  and  shooting  stars  with  their 
graceful  flight,  captivate  us  with  a  mysterious  and  some- 
times fantastic  attraction.  We  gladly  allow  our  thoughts, 
mute  questioners  of  the  mysteries  of  the  firmament,  to 
rest  upon  the  brilliant,  golden  trail  they  leave  behind 
them.  These  unknown  travelers  bring  a  message  from 
eternity;  they  tell  us  the  tale  of  their  distant  journeys. 
Children  of  space,  their  ethereal  beauty  speaks  of  the 
immensity  of  the  universe. 

The  eclipses,  on  the  other  hand,  are  phenomena  that 
touch  us  more  nearly,  and  take  place  in  our  vicinity. 

In  treating  of  them,  we  remain  between  the  Earth 
and  the  Moon,  in  our  little  province,  and  witness  the 
picturesque  effects  of  the  combined  movements  of  our 
satellite  around  us. 

Have  you  ever  seen  a  total  eclipse  of  the  Sun  ? 
18  259 


ASTRONOMY  FOR  AMATEURS 

The  sky  is  absolutely  clear:  no  fraction  of  cloud 
shadows  the  solar  rays.  The  azure  vault  of  the  firma- 
ment crowns  the  Earth  with  a  dome  of  dazzling  light. 
The  fires  of  the  orb  of  day  shed  their  beneficent  influence 
generally  upon  the  world. 

Yet,  see!  The  radiance  diminishes.  The  luminous 
disk  of  the  Sun  is  gradually  corroded.  •  Another  disk,  as 
black  as  ink,  creeps  in  front  of  it,  and  little  by  little 
invades  it  entirely.  The  atmosphere  takes  on  a  wan, 
sepulchral  hue;  astonished  nature  is  hushed  in  pro- 
found silence;  an  immense  veil  of  sadness  spreads  over 
the  world.  Night  comes  on  suddenly,  and  the  stars 
shine  out  in  the  Heavens.  It  seems  as  though  by  some 
mysterious  cataclysm  the  Sun  had  disappeared  forever. 
But  this  tribulation  is  soon  over.  The  divine  orb  is  not 
extinct.  A  flaming  jet  emerges  from  the  shadow,  an- 
nouncing his  return,  and  when  he  reappears  we  see 
that  he  has  lost  nothing  in  splendor  or  beauty.  He  is 
still  the  radiant  Apollo,  King  of  Day,  watching  over  the 
life  of  the  planetary  worlds. 

This  sudden  night,  darkening  the  Heavens  in  the 
midst  of  a  fine  day,  can  not  fail  to  produce  a  vivid  im- 
pression upon  the  spectators  of  the  superb  phenomenon. 

The  eclipse  lasts  only  for  a  few  moments,  but  long 
enough  to  make  a  deep  impression  upon  our  minds,  and 
indeed  to  inspire  anxious  spirits  with  terror  and  agita- 

260 


THE  ECLIPSES 

tion — even  at  this  epoch,  when  we  know  that  there  is 
nothing  supernatural  or  formidable  about  it. 

In  former  days.  Humanity  would  have  trembled,  in 
uneasy  consternation.  Was  it  a  judgment  from  Heaven  ? 
Must  it  not  be  the  work  of  some  invisible  hand  throwing 
the  somber  veil  of  night  over  the  celestial  torch  ? 

Had  not  the  Earth  strayed  off  her  appointed  path, 
and  were  we  not  all  to  be  deprived  eternally  of  the  light 
of  our  good  Sun  ?  Was  some  monstrous  dragon  perhaps 
preparing  to  devour  the  orb  of  day  ? 

The  fable  of  the  dragon  devouring  the  Sun  or  Moon 
during  the  eclipses  is  universal  in  Asia  as  in  Africa,  and 
still  finds  acceptance  under  more  than  one  latitude 
But  our  readers  already  know  that  we  may  identify  the 
terrible  celestial  dragon  with  our  gentle  friend  the 
Moon,  who  would  not  be  greatly  flattered  by  the  com- 
parison. 

We  saw  in  the  preceding  lesson  that  the  Moon 
revolves  round  us,  describing  an  almost  circular  orbit 
that  she  travels  over  in  about  a  month.  In  consequence 
of  this  motion,  the  nocturnal  orb  is  sometimes  between 
the  Sun  and  the  Earth,  sometimes  behind  us,  sometimes 
at  a  right  angle  in  relation  to  the  Sun  and  the  Earth. 
Now,  the  eclipses  of  the  Sun  occur  invariably  at  the  time 
of  New  Moon,  when  our  satellite  passes  between  the  Sun 
and  ourselves,  and  the  eclipses  of  the  Moon,  at  the 

261 


ASTRONOMY  FOR  AMATEURS 

moment  of  Full  Moon,  when  the  latter  is  opposite  to  the 
Sun,  and  behind  us. 

This  fact  soon  enabled  the  astronomers  of  antiquity 
to  discover  the  causes  to  which  eclipses  are  due. 

The  Moon,  passing  at  the  beginning  of  its  revolution 
between  the  Sun  and  the  Earth,  may  conceal  a  greater 
or  lesser  portion  of  the  orb  of  day.  In  this  case  there  is 
an  eclipse  of  the  Sun.  On  the  other  hand,  when  it  is 
on  the  other  side  of  the  Earth  in  relation  to  the  Sun,  at 
the  moment  of  Full  Moon,  our  planet  may  intercept  the 
solar  rays,  and  prevent  them  from  reaching  our  satellite. 
The  Moon  is  plunged  into  the  shadow  of  the  Earth,  and 
is  then  eclipsed.  Such  is  the  very  simple  explanation 
of  the  phenomenon.  But  why  is  there  not  an  eclipse  of 
the  Sun  at  each  New  Moon,  and  an  eclipse  of  the  Moon 
at  each  Full  Moon  ? 

If  the  Moon  revolved  round  us  in  the  same  plane  as 
the  Earth  round  the  Sun,  it  would  eclipse  the  Sun  at 
each  New  Moon,  and  would  be  itself  eclipsed  in  our 
shadow  at  each  Full  Moon.  But  the  plane  of  the  lunar 
orbit  dips  a  little  upon  the  plane  of  the  terrestrial  orbit, 
and  the  eclipses  can  only  be  produced  when  the  New 
Moon  or  the  Full  Moon  occur  at  the  line  of  intersection 
of  these  two  planes,  i.  e.y  when  the  Sun,  the  Moon,  and 
the  Earth  are  upon  the  same  straight  line.  In  the  ma- 
jority of  cases,  instead  of  interposing  itself  directly  in 

262 


THE  ECLIPSES 

front  of  the  sovereign  of  our  system,  our  satellite  passes 
a  little  above  or  a  little  below  him,  just  as  its  passage 
behind  us  is  nearly  always  effected  a  little  above  or 
below  the  cone  of  shadow  that  accompanies  our  planet, 
opposite  the  Sun. 

When  the  Moon  intervenes  directly  in  front  of  the 
Sun,  she  arrests  the  light  of  the  radiant  orb,  and  con- 
ceals a  greater  or  less  portion  of  the  solar  disk.  The 
eclipse  is  partial  if  the  Moon  covers  only  a  portion  of 
the  Sun;  total  if  she  covers  it  entirely;  annular,  if  the 
solar  disk  is  visible  all  round  the  lunar  disk,  as  appears 
when  the  Moon,  in  her  elliptical  orbit,  is  beyond  medium 
distance,  toward  the  apogee. 

On  the  other  hand,  when  the  Moon  arrives  imme- 
diately within  the  cone  of  shadow  that  the  Earth  projects 
behind  it,  it  is  her  turn  to  be  eclipsed.  She  no  longer 
receives  the  rays  of  the  Sun,  and  this  deprivation  is  the 
more  marked  in  that  she  owes  all  her  brilliancy  to  the 
light  of  the  orb  of  day.  The  Moon's  obscurity  is  com- 
plete if  she  is  entirely  plunged  into  the  cone  of  shadow. 
In  this  case,  the  eclipse  is  total.  But  if  a  portion  of  her 
disk  emerges  from  the  cone,  that  part  remains  illumi- 
nated while  the  light  of  the  other  dies  out.  In  that  case 
there  is  a  partial  eclipse,  and  the  rounded  form  of  the 
Earth's  shadow  can  be  seen  projected  upon  our  satellite, 
a  celestial  witness  to  the  spherical  nature  of  our  globe. 

263 


ASTRONOMY  FOR  AMATEURS 

Under  certain  conditions,  then,  the  Moon  can 
deprive  us  of  the  luminous  rays  of  the  Sun,  by  con- 
cealing the  orb  of  day,  and  in  other  cases  is  herself 
effaced  in  crossing  our  shadow.  Despite  the  fables, 
fears,  and  anxieties  it  has  engendered,  this  phenomenon 
is  perfectly  natural:  the  Moon  is  only  playing  hide-and- 
seek  with  us — a  very  harmless  amusement,  as  regards 
the  safety  of  our  planet. 

But  as  we  said  just  now,  these  phenomena  formerly 
had  the  power  of  terrifying  ignorant  mortals,  either 
when  the  orb  of  light'  and  life  seemed  on  the  verge  of 
extinction,  or  when  the  beautiful  Phoebus  was  covered 
with  a  veil  of  crape  and  woe,  or  took  on  a  deep  cop- 
pery hue. 

It  would  take  a  volume  to  describe  all  the  notable 
events  which  have  been  influenced  by  eclipses,  some- 
times for  good,  more  often  with  disastrous  consequences 
The  recital  of  these  tragic  stories  would  not  be  devoid  of 
interest;  it  would  illustrate  the  possibilities  of  ignorance 
and  superstition,  and  the  power  man  gains  from  intel- 
lectual culture  and  scientific  study. 

Herodotus  records  that  the  Scythians,  having  some 
grievance  against  Cyaxarus,  King  of  the  Medes,  re- 
venged themselves  by  serving  up  the  limbs  of  one  of  his 
children,  whom  they  had  murdered,  at  a  banquet  as 
rare  game.  The  scoundrels  who  committed  this  atro- 

264 


THE  ECLIPSES 

cious  crime  took  refuge  at  the  Court  of  the  King  of 
Lydia,  who  was  ill  judged  enough  to  protect  them. 
War  was  accordingly  declared  between  the  Medes  and 
Lydians,  but  a  total  eclipse  of  the  Sun  occurring  just 
when  the  battle  was  imminent,  had  the  happy  effect  of 
disarming  the  combatants,  who  prudently  retired  each 
to  their  own  country.  This  eclipse,  which  seems  to 
have  occurred  on  May  28,  584  B.  c.,  had  been  predicted 
by  Thales.  The  French  painter  Rochegrosse  has 
painted  a  striking  picture  of  the  scene  (Fig.  75). 

In  the  year  413  B.  c.  the  Athenian  General  Nicias 
prepared  to  return  to  Greece  after  an  expedition  to 
Sicily.  But,  terrified  by  an  eclipse  of  the  Moon,  and 
fearing  the  malign  influence  of  the  phenomenon,  he  put 
off  his  departure,  and  lost  the  chance  of  retreat.  This 
superstition  cost  him  his  life.  The  Greek  army  was 
destroyed,  and  this  event  marks  the  commencement  of 
the  decadence  of  Athens. 

In  331  B.  c.  an  eclipse  of  the  Moon  disorganized  the 
troops  of  Alexander,  near  Arbela,  and  the  great  Mace- 
donian Captain  had  need  of  all  his  address  to  reassure 
his  panic-stricken  soldiers. 

Agathocles,  King  of  Syracuse,  blocked  by  the  Car- 
thaginians in  the  port  of  this  city,  had  the  good  fortune 
to  escape,  but  was  disturbed  on  the  second  day  of  his 
flight  by  the  arrival  of  a  total  eclipse  of  the  Sun  which 

265 


ASTRONOMY  FOR  AMATEURS 

alarmed  his  companions.     "What  are  you  afraid  of?" 
said  he,  spreading  his  cloak  in  front  of  the  Sun.    "Are 


FIG.  75. — Battle  between  the  Medes  and  Lydians  arrested 
by  an  Eclipse  of  the  Sun. 

266 


THE  ECLIPSES 

you  alarmed  at  a  shadow?"  (This  eclipse  seems  to  be 
that  of  August  15,  309,  rather  than  that  of  March  2, 

310-) 

On  June  29,  1033,  an  epoch  at  which  the  approaching 

end  of  the  world  struck  terror  into  all  hearts,  an  annular 
eclipse  of  the  Sun  occurring  about  midday  frustrated 
the  designs  of  a  band  of  conspirators  who  intended  to 
strangle  the  Pope  at  the  altar.  This  Pope  was  Bene- 
dict IX,  a  youth  of  less  than  twenty,  whose  conduct 
is  said  to  have  been  anything  but  exemplary.  The 
assassins,  terrified  at  the  darkening  of  the  Sun,  dared 
not  touch  the  Pontiff,  and  he  reigned  till  1044.* 

On  March  I,  1504,  a  lunar  eclipse  saved  the  life  of 
Christopher  Columbus.  He  was  threatened  with  death 
by  starvation  in  Jamaica,  where  the  contumacious 
savages  refused  to  give  him  provisions.  Forewarned  of 
the  arrival  of  this  eclipse  by  the  astronomical  almanacs, 
he  threatened  to  deprive  the  Caribs  of  the  light  of  the 
Moon  —  and  kept  his  word.  The  eclipse  had  hardly 
begun  when  the  terrified  Indians  flung  themselves  at  his 
feet,  and  brought  him  all  that  he  required. 

In  all  times  and  among  all  people  we  find  traces  of 
popular  superstitions  connected  with  eclipses.  Here, 
the  abnormal  absence  of  the  Moon's  light  is  regarded 
as  a  sign  of  divine  anger:  the  humble  penitents  betake 

*  "La  fin  du  Monde."      Flammarion,    p.  186. 
267 


ASTRONOMY  FOR  AMATEURS 

themselves  to  prayer  to  ward  off  the  divine  anger. 
There,  the  cruelty  of  the  dread  dragon  is  to  be  averted: 
he  must  be  chased  away  by  cries  and  threats,  and  the 
sky  is  bombarded  with  shots  to  deliver  the  victim  from 
his  monstrous  oppressor. 

In  France  the  announcement  of  a  solar  eclipse  for 
August  21,  1560,  so  greatly  disturbed  our  ancestors' 
peace  of  mind  as  to  make  them  idiotic.  Preparations* 
were  made  for  assisting  at  an  alarming  phenomenon 
that  threatened  Humanity  with  deadly  consequences! 
The  unhappy  eclipse  had  been  preceded  by  a  multitude 
of  ill  omens!  Some  expected  a  great  revolution  in  the 
provinces  and  in  Rome,  others  predicted  a  new  universal 
deluge,  or,  on  the  other  hand,  the  conflagration  of  the 
world;  the  most  optimistic  thought  the  air  would  be 
contaminated.  To  preserve  themselves  from  so  many 
dangers,  and  in  accordance  with  the  physicians'  orders, 
numbers  of  frightened  people  shut  themselves  up  in 
tightly  closed  and  perfumed  cellars,  where  they  awaited 
the  decrees  of  Fate.  The  approach  of  the  phenomenon 
increased  the  panic,  and  it  is  said  that  one  village  cure, 
being  unable  to  hear  the  confessions  of  all  his  flock, 
who  wanted  to  discharge  their  souls  of  sin  before  taking 
flight  for  a  better  world,  was  fain  to  tell  them  "there  was 
no  hurry,  because  the  eclipse  had  been  put  off  a  fort- 
night on  account  of  the  number  of  penitents"! 

268 


THE  ECLIPSES 

These  fears  and  terrors  are  still  extant  among 
ignorant  peoples.  In  the  night  of  February  27,  1877, 
an  eclipse  of  the  Moon  produced  an  indescribable  panic 


FIG.  76.— -Eclipse  of  the  Moon  at  Laos  (February  27,  1877). 

among  the  inhabitants  of  Laos  (Indo-China).  In  order 
to  frighten  off  the  Black  Dragon,  the  natives  fired  shots 
at  the  half-devoured  orb,  accompanying  their  volley  with 

269 


ASTRONOMY  FOR  AMATEURS 

the  most  appalling  yells.  Dr.  Harmand  has  memo- 
rialized the  scene  in  the  lively  sketch  given  on  p.  269. 

During  the  solar  eclipse  of  March  15,  1877,  an  an- 
alogous scene  occurred  among  the  Turks,  who  for  the 
moment  forgot  their  preparations  for  war  with  Russia, 
in  order  to  shoot  at  the  Sun,  and  deliver  him  from  the 
toils  of  the  Dragon. 

The  lunar  eclipse  of  December  16,  1880,  was  not 
unnoticed  at  Tackhent  (Russian  Turkestan),  where  it 
was  received  with  a  terrific  din  of  saucepans,  samovars 
and  various  implements  struck  together  again  and  again 
by  willing  hands  that  sought  to  deliver  the  Moon  from 
the  demon  Tchaitan  who  was  devouring  her. 

In  China,  eclipses  are  the  object  of  imposing  cere- 
monies, whose  object  is  to  reestablish  the  regularity  of 
the  celestial  motions.  Since  the  Emperor  is  regarded 
as  the  Son  of  Heaven,  his  government  must  in  some  sort 
be  a  reflection  of  the  immutable  order  of  the  sidereal 
harmonies.  As  eclipses  were  regarded  by  astrologers 
as  disturbances  of  the  divine  order,  their  appearance 
indicates  some  irregularity  in  the  government  of  the 
Celestial  Empire.  Accordingly,  they  are  received  with 
all  kinds  of  expiatory  ceremonies  prescribed  thousands 
of  years  ago,  and  still  in  force  to-day. 

In  the  twentieth  century,  as  in  the  nineteenth,  the 
eighteenth,  or  in  ancient  epochs,  the  same  awe  and  terror 

270 


THE  ECLIPSES 

operates  upon  the  ignorant  populations  who  abound 
upon  the  surface  of  our  planet. 

To  return  to  astronomical  realities. 

We  said  above  that  these  phenomena  were  produced 
when  the  Full  Moon  and  the  New  Moon  reached  the 
line  of  intersection,  known  as  the  line  of  nodes,  when 
the  plane  of  the  lunar  orbit  cuts  the  plane  of  the 
ecliptic.  As  this  line  turns  and  comes  back  in  the  same 
direction  relatively  to  the  Sun  at  the  end  of  eighteen 
years,  eleven  days,  we  have  only  to  register  the  eclipses 
observed  during  this  period  in  order  to  know  all  that 
will  occur  in  the  future,  and  to  find  such  as  happened 
in  the  past.  This  period  was  known  to  the  Greeks 
under  the  name  of  the  Metonic  Cycle,  and  the  Chal- 
deans employed  it  three  thousand  years  ago  under  the 
name  of  Saros. 

On  examining  this  cycle,  composed  of  223  lunations, 
we  see  that  there  can  not  be  more  than  seven  eclipses  in 
one  year,  nor  less  than  two.  When  there  are  only  two, 
they  are  eclipses  of  the  Sun. 

The  totality  of  a  solar  eclipse  can  not  last  more  than 
seven  minutes,  fifty-eight  seconds  at  the  equator,  and 
six  minutes,  ten  seconds  in  the  latitude  of  Paris.  The 
Moon,  on  the  contrary,  may  be  entirely  eclipsed  for 
nearly  two  hours. 

Eclipses  of  the  Sun  are  very  rare  for  a  definite  spot. 
271 


ASTRONOMY  FOR  AMATEURS 

Thus  not  one  occurred  for  Paris  during  the  whole  of  the 
nineteenth  century,  the  last  which  happened  exactly 
above  the  capital  of  France  having  been  on  May  22, 
1724.  I  have  calculated  all  those  for  the  twentieth  cen- 
tury, and  find  that  two  will  take  place  close  to  Paris,  on 
April  17,  1912,  at  eighteen  minutes  past  noon  (total  for 
Choisy-le-Roi,  Longjumeau,  and  Dourdan,  but  very 
brief:  seven  seconds),  and  August  11,  1999,  at  10.28 
A.  M.  (total  for  Beauvais,  Compiegne,  Amiens,  St. 
Quentin,  fairly  long:  two  minutes,  seventeen  seconds). 
Paris  itself  will  not  be  favored  before  August  12,  2026. 
In  order  to  witness  the  phenomenon,  one  must  go  and 
look  for  it.  This  the  author  did  on  May  28,  1900,  in 
Spain. 

The  progress  of  the  lunar  shadow  upon  the  surface 
of  the  Earth  is  traced  beforehand  on  maps  that  serve 
to  show  the  favored  countries  for  which  our  satellite  will 
dispense  her  ephemeral  night.  The  above  figure  shows 
the  trajectory  of  the  total  phase  of  the  1900  eclipse  in 
Portugal,  Spain,  Algeria,  and  Tunis. 

The  immutable  splendor  of  the  celestial  motions  had 
never  struck  the  author  so  impressively  as  during  the 
observation  of  this  grandiose  phenomenon.  With  the 
absolute  precision  of  astronomical  calculations,  our 
satellite,  gravitating  round  the  Earth,  arrived  upon  the 
theoretical  line  drawn  from  the  orb  of  day  to  our  planet, 

272 


00 
N 

£ 

§ 

O 

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273 


ASTRONOMY  FOR  AMATEURS 

and  interposed  itself  gradually,  slowly,  and  exactly,  in 
front  of  it.  The  eclipse  was  total,  and  occurred  at  the 
moment  predicted  by  calculation.  Then  the  obscure 
globe  of  the  Moon  pursued  its  regular  course,  discovered 
the  radiant  orb  behind,  and  gradually  and  slowly  com- 
pleted its  transit  in  front  of  him.  Here,  to  all  observers, 
was  a  double  philosophical  lesson,  a  twofold  impression: 
that  of  the  greatness,  the  omnipotence  of  the  inexorable 
forces  that  govern  the  universe,  and  that  of  the  inex- 
orable valor  of  man,  of  this  thinking  atom  straying  upon 
another  atom,  who  by  the  travail  of  his  feeble  intelligence 
has  arrived  at  the  knowledge  of  the  laws  by  which  he, 
like  the  rest  of  the  world,  is  borne  away  through  space, 
through  time,  and  through  eternity. 

The  line  of  centrality  passed  through  Elche,  a  pic- 
turesque city  of  30,000  inhabitants,  not  far  from  Ali- 
cante, and  we  had  chosen  this  for  our  station  on 
account  of  the  probability  of  fine  weather. 

From  the  terrace  of  the  country  house  of  the  hos- 
pitable Mayor,  a  farm  transformed  into  an  observatory 
by  our  learned  friend,  Count  de  la  Baume  Pluvinel, 
there  were  no  obstacles  between  ourselves  and  any  part 
of  the  sky  or  landscape.  The  whole  horizon  lay  before 
us.  In  front  was  a  town  of  Arab  aspect  framed  in  a 
lovely  oasis  of  palm-trees;  a  little  farther  off,  the  blue  sea 
beyond  the  shores  of  Alicante  and  Murcia :  on  the  other 

274 


THE  ECLIPSES 

side  a  belt  of  low  mountains,  and  near  us  fields  and 
gardens.  A  Company  of  the  Civic  Guard  kept  order, 
and  prevented  the  entrance  of  too  many  curious  visitors, 
of  whom  over  ten  thousand  had  arrived. 

At  the  moment  when  the  first  contact  of  the  lunar 
disk  with  the  solar  disk  was  observed  in  the  telescope, 
we  fired  a  gun,  in  order  to  announce  the  precise  com- 
mencement of  the  occultation  to  the  40,000  persons  who 
were  awaiting  the  phenomenon,  and  to  discover  what 
difference  would  exist  between  this  telescopic  observa- 
tion and  those  made  with  the  unaided  eyes  (protected 
simply  by  a  bit  of  smoked  glass)  of  so  many  improvised 
spectators.  .This  had  already  been  done  by  Arago  at 
Perpignan  in  1842.  The  verification  was  almost  im- 
mediate for  the  majority  of  eyes,  and  may  be  estimated 
at  eight  or  ten  seconds.  So  that  the  commencement  of 
the  eclipse  was  confirmed  almost  as  promptly  for  the 
eye  as  with  the  astronomical  instruments. 

The  sky  was  splendidly  clear;  no  cloud,  no  mist, 
deep  blue;  blazing  Sun.  The  first  period  of  the  eclipse 
showed  nothing  particular.  It  is  only  from  the  mo- 
ment when  more  than  half  the  solar  disk  is  covered  by 
the  lunar  disk  that  the  phenomenon  is  imposing  in  its 
grandeur.  At  this  phase,  I  called  the  attention  of  the 
people  standing  in  the  court  to  the  visibility  of  the 
stars,  and  indicating  the  place  of  Venus  in  the  sky  asked 
19  275 


ASTRONOMY  FOR  AMATEURS 

if  any  with  long  sight  could  perceive  her.  Eight  at  once 
responded  in  the  affirmative.  It  should  be  said  that  the 
planet  was  at  that  time  at  its  period  of  maximum  bril- 
liancy, when  for  observers  blessed  with  good  sight,  it  is 
always  visible  to  the  unaided  eye. 

When  some  three-quarters  of  the  Sun  were  eclipsed, 
the  pigeons  which  had  flown  back  to  the  farm  huddled 
into  a  corner,  and  made  no  further  movement.  They 
told  me  that  evening  that  the  fowls  had  done  the  same 
a  little  later,  returning  to  the  hen-house  as  though  it 
had  been  night,  and  that  the  small  children  (who  were 
very  numerous  at  Elche,  where  the  population  is  cer- 
tainly not  diminishing)  left  off  their  games,  and  came 
back  to  their  mothers'  skirts.  The  birds  flew  anxious- 
ly to  their  nests.  The  ants  in  one  garden  were  exces- 
sively agitated,  no  doubt  disconcerted  in  their  strategics. 
The  bats  came  out. 

A  few  days  before  the  eclipse  I  had  prepared  the 
inhabitants  of  this  part  of  Spain  for  the  observation  of 
the  phenomenon  by  the  following  description,  which 
sums  up  the  previous  accounts  of  the  astronomers: 

"The  spectacle  of  a  total  eclipse  of  the  Sun  is  one 
of  the  most  magnificent  and  imposing  that  it  is  possible 
to  see  in  nature.  At  the  exact  moment  indicated  by 
calculation,  the  Moon  arrives  in  front  of  the  Sun,  eats 
into  it  gradually,  and  at  last  entirely  covers  it.  The 

276 


THE  ECLIPSES 

light  of  the  day  lessens  and  is  transformed.  A  sense 
of  oppression  is  felt  by  all  nature,  the  birds  are  hushed, 
the  dog  takes  refuge  with  his  master,  the  chickens  hide 
beneath  their  mother's  wing,  the  wind  drops,  the  tem- 
perature falls,  an  appalling  stillness  is  everywhere  per- 
ceptible, as  though  the  universe  were  on  the  verge  of 
some  imminent  catastrophe.  Men's  faces  assume  a 
cadaverous  hue  similar  to  that  given  at  night  by  the 
flame  of  spirits  of  wine  and  salt,  a  livid  funereal  light, 
the  sinister  illumination  of  the  world's  last  hour. 

"At  the  moment  when  the  last  line  of  the  solar  cres- 
cent disappears,  we  see,  instead  of  the  Sun,  a  black  disk 
surrounded  with  a  splendid  luminous  aureole  shooting 
immense  jets  into  space,  with  roseate  flames  burning 
at  the  base. 

"A  sudden  night  has  fallen  on  us,  a  weird,  wan  night 
in  which  the  brightest  of  the  stars  are  visible  in  the 
Heavens.  The  spectacle  is  splendid,  grandiose,  solemn, 
and  sublime." 

This  impression  was  actually  felt  by  us  all,  as 
may  be  seen  from  the  following  notes,  written  in  my 
schedule  of  observation  during  the  event,  or  immedi- 
ately after: 

"  3-5°  p-  M-  Light  very  weak,  sky  leaden  gray, 
mountains  standing  out  with  remarkable  clearness 
from  the  horizon,  and  seeming  to  approach  us. 

277 


ASTRONOMY  FOR  AMATEURS 

"  3-55  p-  M-  Fall  °f  temperature  very  apparent. 
Cold  wind  blowing  through  the  atmosphere. 

"3.56  P.  M.  Profound  silence  through  nature, 
which  seems  to  participate  in  the  celestial  phenomenon. 
Silence  in  all  the  groups. 

"  3-57  P-  M-  Light  considerably  diminished,  becom- 
ing wan,  strange,  and  sinister.  Landscape  leaden  gray, 
sea  looks  black.  This  diminution  of  light  is  not  that  of 
every  day  after  the  sunset.  There  is,  as  it  were,  a  tint  of 
sadness  spread  over  the  whole  of  nature.  One  becomes 
accustomed  to  it,  and  yet  while  we  know  that  the  occulta- 
tion  of  the  Sun  by  the  Moon  is  a  natural  phenomenon, 
we  can  not  escape  a  certain  sense  of  uneasiness.  The 
approach  of  some  extraordinary  spectacle  is  imminent." 

At  this  point  we  examined  the  effects  of  the  solar 
light  upon  the  seven  colors  of  the  spectrum.  In  order 
to  determine  as  accurately  as  possible  the  tonality  of 
the  light  of  the  eclipse,  I  had  prepared  seven  great  sheets, 
each  painted  boldly  in  the  colors  of  the  spectrum,  violet, 
indigo,  blue,  green,  yellow,  orange,  red;  and  a  similar 
series  in  pieces  of  silk.  These  colors  were  laid  at  our 
feet  upon  the  terrace  where  my  wife,  as  well  as  Countess 
de  la  Baume,  were  watching  with  me.  We  then  saw  the 
first  four  disappear  successively  and  entirely  and  turn 
black  in  a  few  seconds,  in  the  following  order:  violet, 
indigo,  blue,  green.  The  three  other  colors  were  con- 

278 


THE  ECLIPSES 

siderably    attenuated    by   the    darkness,  but    remained 
visible. 

It  should  be  noted  that  in  the  normal  order  of  things 
— that  is,  every  evening — the  contrary  appears;  violet 
remains  visible  after  the  red. 

This  experiment  shows  that  the  last  light  emitted 
by  the  eclipsed  Sun  belongs  to  the  least  refrangible  rays, 
to  the  greatest  wave-lengths,  to  the  slowest  vibrations, 
to  the  yellow  and  red  rays.  Such  therefore  is  the  pre- 
dominating color  of  the  solar  atmosphere. 

This  experiment  completed,  we  turn  back  to  the 
Sun.  Magical  and  splendid  spectacle  f  Totality  has 
commenced,  the  Sun  has  disappeared,  the  black  disk 
of  the  Moon  covers  it  entirely,  leaving  all  round  it  a 
magnificent  corona  of  dazzling  light.  One  would  sup- 
pose it  to  be  an  annular  eclipse,  with  the  difference  that 
this  can  be  observed  with  the  naked  eye,  without  fatigue 
to  the  retina,  and  drawn  quietly. 

This  luminous  coronal  atmosphere  entirely  sur- 
rounds the  solar  disk,  at  a  pretty  equal  depth,  equivalent 
to  about  the  third  of  half  the  solar  diameter.  It  may 
be  regarded  as  the  Sun's  atmosphere. 

Beyond  this  corona  is  an  aureole,  of  vaster  glory  but 
less  luminous,  which  sends  out  long  plumes,  principally 
in  the  direction  of  the  equatorial  zone  of  the  Sun,  and  of 
the  belt  of  activity  of  the  spots  and  prominences. 

279 


ASTRONOMY  FOR  AMATEURS 

At  the  summit  of  the  disk  it  is  conical  in  shape. 
Below  it  is  double,  and  its  right-hand  portion  ends  in  a 
point,  not  far  from  Mercury,  which  shines  like  a  dazzling 
star  of  first  magnitude,  and  seems  placed  there  expressly 
to  give  us  the  extent  and  direction  of  the  solar  aureole. 

I  draw  these  various  aspects  (which,  moreover, 
change  with  the  movement  of  the  Moon),  and  what 
strikes  me  most  is  the  distinction  in  light  between  this 
aureole  and  the  coronal  atmosphere;  the  latter  appears 
to  be  a  brilliant  silvery  white,  the  former  is  grayer  and 
certainly  less  dense. 

My  impression  is  that  there  are  two  solar  envelopes 
of  entirely  different  nature,  the  corona  belonging  to  the 
globe  of  the  Sun,  and  forming  its  atmosphere  properly 
so-called,  very  luminous;  the  aureole  formed  of  particles 
that  circulate  independently  round  it,  probably  arising 
from  eruptions,  their  form  as  a  whole  being  possibly  due 
to  electric  or  magnetic  forces,  counterbalanced  by  re- 
sistances of  various  natures.  In  our  own  atmosphere 
the  volcanic  eruptions  are  distinct  from  the  aerial 
envelope. 

The  general  configuration  of  this  external  halo, 
spreading  more  particularly  in  the  equatorial  zone,  is 
sufficiently  like  that  of  the  eclipse  of  1889,  published  in 
my  Popular  Astronomy,  which  also  corresponded  with 
a  minimum  of  solar  energy.  The  year  1900  is  in  fact 

280 


FIG.  78. — Total  eclipse  of  the  Sun,  May  28,  1900, 

as  observed  from  Elche  (Spain). 


28l 


ASTRONOMY  FOR  AMATEURS 

close  upon  the  mimimum  of  the  eleven-year  period. 
This  equatorial  form  is,  moreover,  what  all  the  astrono- 
mers were  expecting. 

There  can  no  longer  be  the  slightest  doubt  that  the 
solar  envelope  varies  with  the  activity  of  the  Sun.  .  .  . 

"  But  the  total  eclipse  lasted  a  much  shorter  time 
than  I  have  taken  to  write  these  lines.  The  seventy- 
nine  seconds  of  totality  are  over.  A  dazzling  light 
bursts  from  the  Sun,  and  tells  that  the  Moon  pursuing 
its  orbit  has  left  it.  The  splendid  sight  is  over.  It  has 
gone  like  a  shadow. 

"Already  over!  It  is  almost  a  disillusion.  Nothing 
beautiful  lasts  in  this  world.  Too  sad!  If  only  the 
celestial  spectacle  could  have  lasted  two,  three,  or  four 
minutes!  It  was  too  short.  .  .  . 

"Alas!  we  are  forced  to  take  things  as  they  are. 

"The  surprise,  the  oppression,  the  terror  of  some, 
the  universal  silence  are  over.  The  Sun  reappears  in 
his  splendor,  and  the  life  of  nature  resumes  its  momen- 
tarily suspended  course. 

"  While  I  was  making  my  drawing,  M.  I'Abbe 
Moreux,  my  colleague  from  the  Astronomical  Society  of 
France,  who  accompanied  me  to  Spain  for  this  observa- 
tion, was  taking  one  of  his  own,  without  any  reciprocal 
communication.  These  two  sketches  are  alike,  and 
confirmatory. 

282 


THE  ECLIPSES 

"The  differential  thermometers  that  I  exposed  to 
the  Sun,  hanging  freely,  and  protected  from  reflection 
from  the  ground,  were  read  every  five  minutes.  The 
black  thermometer  went  down  from  33.1°  to  20.7°,  that 
is  12.4°;  the  white  from  29°  to  20.2° — that  is,  8.8°.  The 
temperature  in  the  shade  only  varied  three  degrees. 

"The  light  received  during  totality  was  due:  first, 
to  the  luminous  envelope  of  the  Sun;  second,  to  that 
of  the  terrestrial  atmosphere,  illuminated  at  forty  kilo- 
meters (twenty-five  miles)  on  the  one  side  and  the  other 
of  the  line  of  centrality.  It  appeared  to  be  inferior  to 
that  of  the  Full  Moon,  on  account  of  the  almost  sud- 
den transition.  But,  in  reality,  it  was  more  intense, 
for  only  first-magnitude  stars  were  visible  in  the  sky, 
whereas  on  a  night  of  full  moon,  stars  of  second,  and 
even  of  third  magnitude  are  visible.  We  recognized, 
among  others,  Venus,  Mercury,  Sirius,  Procyon,  Ca- 
pella,  Rigel,  Betelgeuse." 

From  these  notes,  taken  on  the  spot,  it  is  evident  that 
the  contemplation  of  a  total  eclipse  of  the  Sun  is  one  of 
the  most  marvelous  spectacles  that  can  be  admired  upon 
our  planet. 

Some  persons  assured  me  that  they  saw  the  shadow 
of  the  Moon  flying  rapidly  over  the  landscape.  My 
attention  was  otherwise  occupied,  and  I  was  unable  to 

283 


ASTRONOMY  FOR  AMATEURS 

verify  this  interesting  observation.  The  shadow  of  the 
Moon  in  effect  took  only  eleven  minutes  (3.47  P.  M.  to 
3.58  P.  M.)  to  traverse  the  Iberian  Peninsula  from  Porto  to 
Alicante,  i.  e.,  a  distance  of  766  kilometers  (475  miles). 
It  must  therefore  have  passed  over  the  ground  at  a 
velocity  of  sixty-nine  kilometers  per  minute,  or  1,150 
meters  per  second,  a  speed  higher  than  that  of  a  bullet. 
It  can  easily  be  watched  from  afar,  on  the  mountains. 

Some  weeks  previous  to  this  fine  eclipse,  when  I  in- 
formed the  Spaniards  of  the  belt  along  which  it  could 
be  observed,  I  had  invited  them  to  note  all  the  interesting 
phenomena  they  might  witness,  including  the  effects 
produced  by  the  eclipse  upon  animals.  Birds  returned 
hurriedly  to  their  nests,  swallows  lost  themselves,  sheep 
huddled  into  compact  packs,  partridges  were  hypnotized, 
frogs  croaked  as  if  it  were  night,  fowls  took  refuge  in  the 
hen-house,  and  cocks  crowed,  bats  came  out,  and  were 
surprised  by  the  sun,  chicks  gathered  under  their 
mothers'  wing,  cage-birds  ceased  their  songs,  some  dogs 
howled,  others  crept  shivering  to  their  masters'  feet,  ants 
returned  to  the  ant-heap,  grasshoppers  chirped  as  at 
sunset,  pigeons  sank  to  the  ground,  a  swarm  of  bees 
went  silently  back  to  their  hive,  and  so  on. 

These  creatures  behaved  as  though  the  night  had 
come,  but  there  were  also  signs  of  fear,  surprise,  even 
of  terror,  differing  only  "in  degree"  from  those  mani- 

284 


THE  ECLIPSES 


Tested  during  the  grandiose  phenomenon  of  a  total 
eclipse  by  human  beings  unenlightened  by  a  scientific 
education. 

At  Madrid  the  eclipse  was  only  partial.  The  young 
King  of  Spain,  Alfonso  XIII,  took  care  to  photograph  it, 
and  I  offer  the  photograph  to  my  readers  (Fig.  79),  as  this 
amiable  sovereign 
did  me  the  honor  to 
give  it  me  a  few  days 
after  the  eclipse. 

The  technical 
results  of  these  ob- 
servations of  solar 
eclipses  relate  more 
especially  to  the 
elucidation  of  the 
grand  problem  of 
the  physical  consti- 
tution of  the  Sun. 
We  alluded  to  them 

in  the  chapter  devoted  to  this  orb.  The  last  great  total 
eclipses  have  been  of  immense  value  to  science. 

The  eclipses  of  the  Moon  are  less  important,  less 
interesting,  than  the  eclipses  of  the  Sun.  Yet  their 
aspect  must  not  be  neglected  on  this  account,  and  it 
may  be  said  to  vary  for  each  eclipse. 

285 


FIG.  79. — The  Eclipse  of  May  28, 
1900,  as  photographed  by  King  Al- 
fonso XIII,  at  Madrid. 


ASTRONOMY  FOR  AMATEURS 

Generally  speaking,  our  satellite  does  not  disappear 
entirely  in  the  Earth's  cone  of  shadow;  the  solar  rays 
are  refracted  round  our  globe  by  our  atmosphere,  and 
curving  inward,  illumine  the  lunar  globe  with  a  rosy 
tint  that  reminds  one  of  the  sunset.  Sometimes,  in- 
deed, this  refraction  does  not  occur,  owing  doubtless 
to  lack  of  transparency  in  the  atmosphere,  and  the 
Moon  becomes  invisible.  This  happened  recently,  on 
April  11,  1903. 

For  any  spot,  eclipses  of  the  Moon  are  incomparably 
more  frequent  than  eclipses  of  the  Sun,  because  the  cone 
of  lunar  shadow  that  produces  the  solar  eclipses  is  not 
very  broad  at  its  contact  with  the  surface  of  the  globe 
(10,  20,  30,  50,  100  kilometers,  according  to  the  distance 
of  the  Moon),  whereas  all  the  countries  of  the  Earth  for 
which  the  Moon  is  above  the  horizon  at  the  hour  of  the 
lunar  eclipse  are  able  to  see  it.  It  is  at  all  times  a 
remarkable  spectacle  that  uplifts  our  thoughts  to  the 
Heavens,  and  I  strongly  advise  my  readers  on  no 
account  to  forego  it. 


286 


CHAPTER  XI 
ON   METHODS 

How   CELEITIAL  DISTANCES  ARE  DETERMINED,  AND  HOW  THE 
SUN  is  WEIGHED 

I  WILL  not  do  my  readers  the  injustice  to  suppose 
that  they  will  be  alarmed  at  the  title  of  this  Lesson,  and 
that  they  do  not  employ  some  "method"  in  their  own 
lives.  I  even  assume  that  if  they  have  been  good  enough 
to  take  me  on  faith  when  I  have  spoken  of  the  distances 
of  the  Sun  and  Moon,  and  Stars,  or  of  the  weight  of 
bodies  at  the  surface  of  Mars,  they  retain  some  curiosity 
as  to  how  the  astronomers  solve  these  problems.  Hence 
it  will  be  as  interesting  as  it  is  useful  to  complete  the 
preceding  statements  by  a  brief  summary  of  the  methods 
employed  for  acquiring  these  bold  conclusions. 

The  Sun  seems  to  touch  the  Earth  when  it  disappears 
in  the  purple  mists  of  twilight:  an  immense  abyss  sepa- 
rates us  from  it.  The  stars  go  hand  in  hand  down  the 
constellated  sky;  and  yet  one  can  not  think  of  their  in- 
conceivable distance  without  a  shiver. 

Our  neighbor,  Moon,  floats  in  space,  a  stone's  throw 

287 


ASTRONOMY  FOR  AMATEURS 

from  us:  but  without  calculation  we  should  never  know 
the  distance,  which  remains  an  impassable  desert  to  us. 

The  best  educated  persons  sometimes  find  it  difficult 
to  admit  that  these  distances  of  Sun  and  Moon  are  better 
determined  and  more  precise  than  those  of  certain  points 
on  our  minute  planet.  Hence,  it  is  of  particular  moment 
for  us  to  give  an  exact  account  of  the  means  employed 
in  determining  them. 

The  calculation  of  these  distances  is  made  by  "trian- 
gulatlon"  This  process  is  the  same  that  surveyors 
use  in  the  measurement  of  terrestrial  distances.  There 
is  nothing  very  alarming  about  it.  If  the  word  repels 
us  a  little  at  first,  it  is  from  its  appearance  only. 

When  the  distance  of  an  object  is  unknown,  the  only 
means  of  expressing  its  apparent  size  is  by  measurement 
of  the  angle  which  it  subtends  before  our  eyes. 

We  all  know  that  an  object  appears  smaller,  in 
proposition  with  its  distance  from  us.  This  diminution 
is  not  a  matter  of  chance.  It  is  geometric,  and  propor- 
tional to  the  distance.  Every  object  removed  to  a  dis- 
tance of  57  times  its  diameter  measures  an  angle  of  I 
degree,  whatever  its  real  dimensions.  Thus  a  sphere  I 
meter  in  diameter  measures  exactly  I  degree,  if  \ve  see 
it  at  a  distance  of  57  feet.  A  statue  measuring  1.80 
meters  (about  5  ft.  8  in.)  will  be  equal  to  an  angle  of  I 
degree,  if  distant  57  times  its  height,  that  is  to  say,  at 

288 


ON  METHODS 

102.60  meters.  A  sheet  of  paper,  size  I  decimeter,  seen 
at  5.70  meters,  represents  the  same  magnitude. 

In  length,  a  degree  is  the  57th  part  of  the  radius  of 
a  circle,  /.  <?.,  from  the  circumference  to  the  center. 

The  measurement  of  an  angle  is  expressed  in  parts 
of  the  circumference.  Now,  what  is  an  angle  of  a  de- 
gree ?  It  is  the  36oth  part  of  any  circumference.  On 
a  table  360  meters  round,  an  angle  of  one  degree  is  a 
centimeter,  seen  from  the  center  of  the  table.  Trace  on 
a  sheet  of  paper  a  circle  0.360 
meters  round — an  angle  of  I 
degree  is  a  millimeter. 

If  the  circumference    of   a 

circus  measuring  180  meters  be       ' l 

.   .  .  FIG.  80. — Measurement 

divided   into   360   places,  each 

of  Angles, 
measuring    0.50    meters     in 

width,  then  when  the  circus  is  full  a  person  placed  at 
the  center  will  see  each  spectator  occupying  an  angle 
of  I  degree.  The  angle  does  not  alter  with  the  dis- 
tance, and  whether  it  be  measured  at  I  meter,  10 
meters,  100  kilometers,  or  in  the  infinite  spaces  of 
Heaven,  it  is  always  the  same  angle.  Whether  a 
degree  be  represented  by  a  meter  or  a  kilometer,  it  al- 
ways remains  a  degree.  As  angles  measuring  less  than 
a  degree  often  have  to  be  calculated,  this  angle  has 
been  subdivided  into  60  parts,  to  which  the  name  of 

289 


ASTRONOMY  FOR  AMATEURS 

minutes  has  been  given,  and  each  minute  into  60  parts 
or  seconds.  Written  short,  the  degree  is  indicated  by 
a  little  zero  (°)  placed  above  the  figure;  the  minute  by 
an  apostrophe  ('),  and  the  second  by  two  (").  These 
minutes  and  seconds  of  arc  have  no  relation  with  the 
same  terms  as  employed  for  the  division  of  the  duration 
of  time.  These  latter  ought  never  to  be  written  with 
the  signs  of  abbreviation  just  indicated,  though  jour- 
nalists nowadays  set  a  somewhat  pedantic  example,  by 
writing,  e.g.,  for  an  automobile  race,4h.  18'  30",  instead 
of  4.h.  i8m.  305. 

This  makes  clear  the  distinction  between  the  relative 
measure  of  an  angle  and  the  absolute  measures,  such, 
for  instance,  as  the  meter.  Thus,  a  degree  may  be 
measured  on  this  page,  while  a  second  (the  3,6ooth  part 
of  a  degree)  measured  in  the  sky  may  correspond  to 
millions  of  kilometers. 

Now  the  measure  of  the  Moon's  diameter  gives  us 
an  angle  of  a  little  more  than  half  a  degree.  If  it  were 
exactly  half  a  degree,  we  should  know  by  that  that  it 
was  114  times  the  breadth  of  its  disk  away  from  us. 
But  it  is  a  little  less,  since  we  have  more  than  half  a 
degree  (3i')»  and  the  geometric  ratio  tells  us  that  the 
distance  of  our  satellite  is  no  times  its  diameter. 

Hence  we  have  very  simply  obtained  a  first  idea  of 
the  distance  of  the  Moon  by  the  measure  of  its  diameter. 

290 


ON  METHODS 

Nothing  could  be  simpler  than  this  method.     The  first 
step  is  made.     Let  us  continue. 

This  approximation  tells  us  nothing  as  yet    of  the 
real  distance  of  the  orb  of  night.     In  order  to  know  this 


FIG.  81. — Division  of  the  Circumference  into  360  degrees. 

distance  in  miles,  we  need  to  know  the  width  in  miles  of 

the  lunar  disk. 

This  problem  has  been  solved,  as  follows: 

Two  observers  go  as  far  as  possible  from  each  other, 

and  observe  the  Moon  simultaneously,  from  two  stations 

situated  on  the  same  meridian,  but  having  a  wide  differ- 
20  291 


ASTRONOMY  FOR  AMATEURS 

ence  of  latitude.  The  distance  that  separates  the  two 
points  of  observation  forms  the  base  of  a  triangle,  of 
which  the  two  long  sides  come  together  on  the  Moon. 

It  is  by  this  proceeding  that  the  distance  of  our 
satellite  was  finally  established,  in  1751  and  1752,  by 
two  French  astronomers,  Lalande  and  Lacaille;  the 
former  observing  at  Berlin,  the  latter  at  the  Cape  of 
Good  Hope.  The  result  of  their  combined  observations 


FIG.  82. — Measurement  of  the  distance  of  the  Moon. 

showed  that  the  angle  formed  at  the  center  of  the  lunar 
disk  by  the  half-diameter  of  the  Earth  is  57  minutes 
of  arc  (a  little  less  than  a  degree).  This  is  known  as 
the  parallax  of  the  Moon. 

Here  is  a  more  or  less  alarming  word;  yet  it  is  one 
that  we  can  not  dispense  with  in  discussing  the  distance 
of  the  stars.  This  astronomical  term  will  soon  become 
familiar  in  the  course  of  the  present  lesson,  where  it 

292 


ON  METHODS 

will  frequently  recur,  and  always  in  connection  with 
the  measurement  of  celestial  distances.  "Do  not  let  us 
fear,"  wrote  Lalande  in  his  Astronomic  des  Dames,  "do 
not  let  us  fear  to  use  the  term  parallax,  despite  its  scien- 
tific aspect;  it  is  convenient,  and  this  term  explains  a 
very  simple  and  very  familiar  effect." 

"If  one  is  at  the  play,"  he  continues,  "behind  a 
woman  whose  hat  is  too  large,  and  prevents  one  from 
seeing  the  stage  [written  a  hundred  years  ago!],  one 
leans  to  the  left  or  right,  one  rises  or  stoops:  all  this  is  a 
parallax,  a  diversity  of  aspect,  in  virtue  of  which  the  hat 
appears  to  correspond  with  another  part  of  the  theater 
from  that  in  which  are  the  actors."  "  It  is  thus,"  he  adds, 
"that  there  may  be  an  eclipse  of  the  Sun  in  Africa  and 
none  for  us,  and  that  we  see  the  Sun  perfectly,  because 
we  are  high  enough  to  prevent  the  Moon's  hiding  it 
from  us." 

See  how  simple  it  is.  This  parallax  of  57  min- 
utes proves  that  the  Earth  is  removed  from  the  Moon 
at  a  distance  of  about  60  times  its  half-diameter  (pre- 
cisely, 60.27).  From  this  to  the  distance  of  the  Moon  in 
kilometers  is  only  a  step,  because  it  suffices  to  multiply 
the  half-diameter  of  the  Earth,  which  is  6,371  kilometers 
(3,950  miles)  by  this  number.  The  distance  of  our 
satellite,  accordingly,  is  6,371  kilometers,  multiplied  by 
60.27 — tnat  is>  3^4j°o°  kilometers  (238,000  miles).  The 

293 


ASTRONOMY  FOR  AMATEURS 

parallax  of  the  Moon  not  only  tells  us  definitely  the  dis- 
tance of  our  planet,  but  also  permits  us  to  calculate  its 
real  volume  by  the  measure  of  its  apparent  volume. 
As  the  diameter  of  the  Moon  seen  from  the  Earth  sub- 
tends an  angle  of  31',  while  that  of  the  Earth  seen  from 
the  Moon  is  114',  the  real  diameter  of  the  orb  of  night 
must  be  to  that  of  the  terrestrial  globe  in  the  relation  of 
273  to  1,000.  That  is  a  little  more  than  a  quarter,  or 
3,480  kilometers  (2,157  miles),  the  diameter  of  our  planet 
being  12,742  kilometers  (7,900  miles). 

This  distance,  calculated  thus  by  geometry,  is  posi- 
tively determined  with  greater  precision  than  that  em- 
ployed in  the  ordinary  measurements  of  terrestrial  dis- 
tances, such  as  the  length  of  a  road,  or  of  a  railway. 
This  statement  may  seem  to  be  a  romance  to  many, 
but  it  is  undeniable  that  the  distance  separating  the 
Earth  from  the  Moon  is  measured  with  greater  care 
than,  for  instance,  the  length  of  the  road  from  Paris  to 
Marseilles,  or  the  weight  of  a  pound  of  sugar  at  the 
grocer's.  (And  we  may  add  without  comment,  that 
the  astronomers  are  incomparably  more  conscientious 
in  their  measurements  than  the  most  scrupulous  shop- 
keepers.) 

Had  we  conveyed  ourselves  to  the  Moon  in  order  to 
determine  its  distance  and  its  diameter  directly,  we 
should  have  arrived  at  no  greater  precision,  and  we 

294 


ON  METHODS 

should,  moreover,  have  had  to  plan  out  a  journey  which 
in  itself  is  the  most  insurmountable  of  all  the  problems. 

The  Moon  is  at  the  frontier  of  our  little  terrestrial 
province :  one  might  say  that  it  traces  the  limits  of  our 
domain  in  space.  And  yet,  a  distance  of  384,000  kilo- 
meters (238,000  miles)  separates  the  planet  from  the 
satellite.  This  space  is  insignificant  in  the  immeasur- 
able distances  of  Heaven:  for  the  Saturnians  (if  such 
exist!)  the  Earth  and  the  Moon  are  confounded  in  one 
tiny  star  ;  but  for  the  inhabitants  of  our  globe,  the  dis- 
tance is  beyond  all  to  which  we  are  accustomed.  Let 
us  try,  however,  to  span  it  in  thought. 

A  cannon-ball  at  constant  speed  of  500  meters 
(547  yards)  per  second  would  travel  8  days,  5  hours  to 
reach  the  Moon.  A  train  started  at  a  speed  of  one 
kilometer  per  minute,  would  arrive  at  the  end  of  an 
uninterrupted  journey  in  384,000  minutes,  or  6,400 
hours,  or  266  days,  16  hours.  And  in  less  than  the 
time  it  takes  to  write  the  name  of  the  Queen  of  Night, 
a  telegraphic  message  would  convey  our  news  to  the 
Moon  in  one  and  a  quarter  seconds. 

Long-distance  travelers  who  have  been  round  the 
world  some  dozen  times  have  journeyed  a  greater 
distance. 

The  other  stars  (beginning  with  the  Sun)  are  in- 
comparably farther  from  us.  Yet  it  has  been  found 

295 


ASTRONOMY  FOR  AMATEURS 

possible  to  determine  their  distances,  and  the  same 
method  has  been  employed. 

But  it  will  at  once  be  seen  that  different  measures 
are  required  in  calculating  the  distance  of  the  Sun,  388 
times  farther  from  us  than  the  Moon,  for  from  here  to 
the  orb  of  day  is  12,000  times  the  breadth  of  our  planet. 
Here  we  must  not  think  of  erecting  a  triangle  with  the 
diameter  of  the  Earth  for  its  base:  the  two  ideal  lines 
drawn  from  the  extremities  of  this  diameter  would 
come  together  between  the  Earth  and  the  Sun;  there 
would  be  no  triangle,  and  the  measurement  would  be 
absurd. 

In  order  to  measure  the  distance  which  separates 
the  Earth  from  the  Sun,  we  have  recourse  to  the  fine 
planet  Venus,  whose  orbit  is  situated  inside  the  terres- 
trial orbit.  Owing  to  the  combination  of  the  Earth's 
motion  with  that  of  the  Star  of  the  Morning  and  Evening, 
the  capricious  Venus  passes  in  front  of  the  Sun  at  the 
curious  intervals  of  8  years,  113}  years  less  8  years, 
8  years,  113^  years  plus  8  years. 

Thus  there  was  a  transit  in  June,  1761,  then  another 
8  years  after,  in  June,  1769.  The  next  occurred  113} 
years  less  8  years,  z.  e.,  105^  years  after  the  preceding, 
in  December,  1874;  the  next  in  December,  1882.  The 
next  will  be  in  June,  2004,  and  June,  2012.  At  these 
eagerly  anticipated  epochs,  astronomers  watch  the  tran- 

296 


ON  METHODS 

sit  of  Venus  across  the  Sun  at  two  terrestrial  stations 
as  far  as  possible  removed  from  each  other,  marking 
the  two  points  at  which  the  planet,  seen  from  their 
respective  stations,  appears  to  be  projected  at  the  same 
moment  on  the  solar  disk.  This  measure  gives  the 
width  of  an  angle  formed  by  two  lines,  which  starting 
from  two  diametrically  opposite  points  of  the  Earth, 
cross  upon  Venus,  and  form  an  identical  angle  upon  the 
Sun.  Venus  is  thus  at  the  apex  of  two  equal  triangles, 
the  bases  of  which  rest,  respectively,  upon  the  Earth  and 


FIG.  83. — Measurement  of  the  distance  of  the  Sun. 

on  the  Sun.  The  measurement  of  this  angle  gives 
what  is  called  the  parallax  of  the  Sun — that  is,  the  angu- 
lar dimension  at  which  the  Earth  would  be  seen  at  the 
distance  of  the  Sun. 

Thus,  it  has  been  found  that  the  half-diameter  of 
the  Earth  viewed  from  the  Sun  measures  8". 82.  Now, 
we  know  that  an  object  presenting  an  angle  of  one 
degree  is  at  a  distance  of  57  times  its  length. 

The  same  object,  if  it  subtends  an  angle  of  a  minute, 
or  the  sixtieth  part  of  a  degree,  indicates  by  the  measure- 

297 


ASTRONOMY  FOR  AMATEURS 

ment  of  its  angle  that  it  is  60  times  more  distant,  i.  e., 
3,438  times. 

Finally,  an  object  that  measures  one  second,  or  the 
sixtieth  part  of  a  minute,  is  at  a  distance  of  206,265 
times  its  length. 

Hence  we  find  that  the  Earth  is  at  a  distance  from 
the  Sun  of  ^68226-^  —  that  is,  23,386  times  its  half-diame- 
ter, that  is,  149,000,000  kilometers  (93,000,000  miles). 
This  measurement  again  is  as  precise  and  certain  as 
that  of  the  Moon. 

I  hope  my  readers  will  easily  grasp  this  simple 
method  of  triangulation,  the  result  of  which  indicates 
to  us  with  absolute  certainty  the  distance  of  the  two 
great  celestial  torches  to  which  we  owe  the  radiant  light 
of  day  and  the  gentle  illumination  of  our  nights. 

The  distance  of  the  Sun  has,  moreover,  been  con- 
firmed by  other  means,  whose  results  agree  perfectly 
with  the  preceding.  The  two  principal  are  based  on 
the  velocity  of  light.  The  propagation  of  light  is  not 
instantaneous,  and  notwithstanding  the  extreme  rapid- 
ity of  its  movements,  a  certain  time  is  required  for  its 
transmission  from  one  point  to  another.  On  the  Earth, 
this  velocity  has  been  measured  as  300,000  kilometers 
(186,000  miles)  per  second.  To  come  from  Jupiter  to 
the  Earth,  it  requires  thirty  to  forty  minutes,  according 
to  the  distance  of  the  planet.  Now,  in  examining  the 

298 


ON  METHODS 

eclipses  of  Jupiter's  satellites,  it  has  been  discovered  that 
there  is  a  difference  of  16  minutes,  34  seconds  in  the 
moment  of  their  occurrence,  according  as  Jupiter  is  on 
one  side  or  on  the  other  of  the  Sun,  relatively  to  the 
Earth,  at  the  minimum  and  maximum  distance.  If  the 
light  takes  16  minutes,  34  seconds  to  traverse  the  terres- 
trial orbit,  it  must  take  less  than  that  time,  or  8  minutes, 
17  seconds,  to  come  to  us  from  the  Sun,  which  is  situated 
at  the  center.  Knowing  the  velocity  of  light,  the  dis- 
tance of  the  Sun  is  easily  found  by  multiplying  300,000 
by  8  minutes,  17  seconds,  or  497  seconds,  which  gives 
about  149,000,000  kilometers  (93,000,000  miles). 

Another  method  founded  upon  the  velocity  of  .light 
again  gives  a  confirmatory  result.  A  familiar  example 
will  explain  it:  Let  us  imagine  ourselves  exposed  to  a 
vertical  rain;  the  degree  of  inclination  of  our  umbrella 
will  depend  on  the  relation  between  our  speed  and  that 
of  the  drops  of  rain.  The  more  quickly  we  run,  the 
more  we  need  to  dip  our  umbrella  in  order  not  to  meet 
the  drops  of  water.  Now  the  same  thing  occurs  for  light. 
The  stars,  disseminated  in  space,  shed  floods  of  light 
upon  the  Heavens.  If  the  Earth  were  motionless,  the 
luminous  rays  would  reach  us  directly.  But  our  planet 
is  spinning,  racing,  with  the  utmost  speed,  and  in  our 
astronomical  observations  we  are  forced  to  follow  its 
movements,  and  to  incline  our  telescopes  in  the  direction 

299 


ASTRONOMY  FOR  AMATEURS 

of  its  advance.  This  phenomenon,  known  under  the 
name  of  aberration  of  light,  is  the  result  of  the  combined 
effects  of  the  velocity  of  light  and  of  the  Earth's  motion. 
It  shows  that  the  speed  of  our  globe  is  equivalent  to 
TuirnF  that  of  light,  /.  e.,  =  about  30  kilometers  (19 
miles)  per  second.  Our  planet  accordingly  accom- 
plishes her  revolution  round  the  Sun  along  an  orbit 
which  she  traverses  at  a  speed  of  30  kilometers  (better 
29^)  per  second,  or  1,770  kilometers  per  minute,  or 
106,000  kilometers  per  hour,  or  2,592,000  kilometers 
per  day,  or  946,080,000  kilometers  (586,569,600  miles) 
in  the  year.  This  is  the  length  of  the  elliptical  path 
described  by  the  Earth  in  her  annual  translation. 

The  length  of  orbit  being  thus  discovered,  one  can 
calculate  its  diameter,  the  half  of  which  is  exactly  the 
distance  of  the  Sun. 

We  may  cite  one  last  method,  whose  data,  based 
upon  attraction,  are  provided  by  the  motions  of  our  sat- 
ellite. The  Moon  is  a  little  disturbed  in  the  regularity 
of  her  course  round  the  Earth  by  the  influence  of  the 
powerful  Sun.  As  the  attraction  varies  inversely  with 
the  square  of  the  distance,  the  distance  may  be  deter- 
mined by  analyzing  the  effect  it  has  upon  the  Moon. 

Other  means,  on  which  we  will  not  enlarge  in  this 
summary  of  the  methods  employed  for  determinations, 
confirm  the  precisions  of  these  measurements  with  cer- 

300 


ON  METHODS 

tainty.  Our  readers  must  forgive  us  for  dwelling  at 
some  length  upon  the  distance  of  the  orb  of  day,  since 
this  measurement  is  of  the  highest  importance;  it  serves 
as  the  base  for  the  valuation  of  all  stellar  distances,  and 
may  be  considered  as  the  meter  of  the  universe. 

This  radiant  Sun  to  which  we  owe  so  much  is  there- 
fore enthroned  in  space  at  a  distance  of  149,000,000  kilo- 
meters (93,000,000  miles)  from  here.  Its  vast  brazier 
must  indeed  be  powerful  for  its  influence  to  be  exerted 
upon  us  to  such  a  manifest  extent,  it  being  the  very 
condition  of  our  existence,  and  reaching  out  as  far  as 
Neptune,  thirty  times  more  remote  than  ourselves  from 
the  solar  focus. 

It  is  on  account  of  its  great  distance  that  the  Sun 
appears  to  us  no  larger  than  the  Moon,  which  is  only 
384,000  kilometers  (238,000  miles)  from  here,  and  is 
itself  illuminated  by  the  brilliancy  of  this  splendid  orb. 

No  terrestrial  distance  admits  of  our  conceiving  of 
this  distance.  Yet,  if  we  associate  the  idea  of  space  with 
the  idea  of  time,  as  we  have  already  done  for  the  Moon, 
we  may  attempt  to  picture  this  abyss.  The  train  cited 
just  now  would,  if  started  at  a  speed  of  a  kilometer  a 
minute,  arrive  at  the  Sun  after  an  uninterrupted  course 
of  283  years,  and  taking  as  long  to  return  to  the  Earth 
the  total  would  be  566  years.  Fourteen  generations  of 
stokers  would  be  employed  on  this  celestial  excursion 

3OI 


ASTRONOMY  FOR  AMATEURS 

before  the  bold  travelers  could  bring  back  news  of  the 
expedition  to  us. 

Sound  is  transmitted  through  the  air  at  a  velocity  of 
340  meters  (1,115  ^eet)  Per  second.  If  our  atmosphere 
reached  to  the  Sun,  the  noise  of  an  explosion  sufficiently 
formidable  to  be  heard  here  would  only  reach  us  at  the 
end  of  13  years,  9  months.  But  the  more  rapid  carriers, 
such  as  the  telegraph,  would  leap  across  to  the  orb  of 
day  in  8  minutes,  17  seconds. 

Our  imagination  is  confounded  before  this  gulf  of 
93,000,000  miles,  across  which  we  see  our  dazzling 
Sun,  whose  burning  rays  fly  rapidly  through  space  in 
order  to  reach  us. 

And  now  let  us  see  how  the  distances  of  the  planets 
were  determined. 

We  will  leave  aside  the  method  of  which  we  have 
been  speaking;  that  now  to  be  employed  is  quite  dif- 
ferent, but  equally  precise  in  its  results. 

It  is  obvious  that  the  revolution  of  a  planet  round  the 
Sun  will  be  longer  in  proportion  as  the  distance  is  greater, 
and  the  orbit  that  has  to  be  traveled  vaster.  This  is 
simple.  But  the  most  curious  thing  is  that  there  is  a 
geometric  proportion  in  the  relations  between  the 
duration  of  the  revolutions  of  the  planets  and  their 
distances.  This  proportion  was  discovered  by  Kepler, 

302 


ON  METHODS 

after  thirty   years   of   research,   and   embodied  in   the 
following  formula: 

"The  squares  of  the  times  of  revolution  of  the  planets 
round  the  Sun  (the  periodic  times)  are  proportional  to 
the  cubes  of  their  mean  distances  from  the  Sun." 

This  is  enough  to  alarm  the  boldest  reader.  And 
yet,  if  we  unravel  this  somewhat  incomprehensible 
phrase,  we  are  struck  with  its  simplicity. 

What  is  a  square  ?  We  all  know  this  much;  it  is 
taught  to  children  of  ten  years  old.  But  lest  it  has  slipped 
your  memory:  a  square  is  simply  a  number  multiplied 
by  itself. 

Thus:  2  X  2  =  4;  4  is  the  square  of  2. 

Four  times  4  is  16;  16  is  the  square  of  4. 

And  so  on,  indefinitely. 

Now,  what  is  a  cube  ?  It  is  no  more  difficult.  It  is 
a  number  multiplied  twice  by  itself. 

For  instance:  2  multiplied  by  2  and  again  by  2  equals 
8.  So  8  is  the  cube  of  2.  3  X  3  X  3  =  27;  27  is  the 
cube  of  3,  and  so  on. 

Now  let  us  take  an  example  that  will  show  the  sim- 
plicity and  precision  of  the  formula  enunciated  above. 
Let  us  choose  a  planet,  no  matter  which.  Say,  Jupiter, 
the  giant  of  the  worlds.  He  is  the  Lord  of  our  planet- 
ary group.  This  colossal  star  is  five  times  (precisely, 
5.2)  as  far  from  us  as  the  Sun. 

303 


ASTRONOMY  FOR  AMATEURS 

Multiply  this  number  twice  by  itself  5.2  X  5.2 
X  5.2  =  140. 

On  the  other  hand,  the  revolution  of  Jupiter  takes 
almost  twelve  years  (11.85).  This  number  multiplied 
by  itself  also  equals  140.  The  square  of  the  number 
1 1.85  is  equal  to  the  cube  of  the  number  5.2.  This  very 
simple  law  regulates  all  the  heavenly  bodies. 

Thus,  to  find  the  distance  of  a  planet,  it  is  sufficient 
to  observe  the  time  of  its  revolution,  then  to  discover 
the  square  of  the  given  number  by  multiplying  it  into 
itself.  The  result  of  the  operation  gives  simultaneously 
the  cube  of  the  number  that  represents  the  distance. 

To  express  this  distance  in  kilometers  (or  miles),  it  is 
sufficient  to  multiply  it  by  149,000,000  (in  miles  93,000,- 
ooo),  the  key  to  the  system  of  the  world. 

Nothing,  then,  could  be  less  complicated  than  the 
definition  of  these  methods.  A  few  moments  of  atten- 
tion reveal  to  us  in  their  majestic  simplicity  the  immut- 
able laws  that  preside  over  the  immense  harmony  of  the 
Heavens. 

But  we  must  not  confine  ourselves  to  our  own  solar 
province.  We  have  yet  to  speak  of  the  stars  that  reign 
in  infinite  space  far  beyond  our  radiant  Sun. 

Strange  and  audacious  as  it  may  appear,  the  human 
mind  is  able  to  cross  these  heights,  to  rise  on  the  wings 

304 


ON  METHODS 

of  genius  to  these  distant  suns,  and  to  plumb  the  depths 
of  the  abyss  that  separates  us  from  these  celestial 
kingdoms. 

Here,  we  return  to  our  first  method,  that  of  triangu- 
iation.  And  the  distance  that  separates  us  from  the 
Sun  must  serve  in  calculating  the  distances  of  the  stars. 

The  Earth,  spinning  round  the  Sun  at  a  distance  of 
149,000,000  kilometers  (93,000,000  miles),  describes  a 
circumference,  or  rather  an  ellipse,  of  936,000,000  kilo- 
meters (580,320,000  miles),  which  it  travels  over  in  a 
year.  The  distance  of  any  point  of  the  terrestrial  orbit 
from  the  diametrically  opposite  point  which  it  passes 
six  months  later  is  298,000,000  kilometers  (184,760,000 
miles),  i.  e.,  the  diameter  of  this  orbit.  This  immense 
distance  (in  comparison  with  those  with  which  we  are 
familiar)  serves  as  the  base  of  a  triangle  of  which  the 
apex  is  a  star. 

The  difficulty  in  exact  measurements  of  the  distance 
of  a  star  consists  in  observing  the  little  luminous  point 
persistently  for  a  whole  year,  to  see  if  this  star  is  sta- 
tionary, or  if  it  describes  a  minute  ellipse  reproducing 
in  perspective  the  annual  revolution  of  the  Earth. 

If  it  remains  fixed,  it  is  lost  in  such  depths  of  space 
that  it  is  impossible  to  gage  the  distance,  and  our 
298,000,000  kilometers  have  no  meaning  in  view  of 
such  an  abyss.  If,  on  the  contrary,  it  is  displaced,  it 

305 


ASTRONOMY  FOR  AMATEURS 


will  in  the  year  describe  a  minute  ellipse,  which  is  only 
the  reflection,  the  perspective  in  miniature,  of  the  revo- 
lution of  our  planet  round  the  Sun. 
The  annual  parallax  of  a  star 
is  the  angle  under  which  one 
would  see  the  radius,  or  half-diam- 
eter, of  the  terrestrial  orbit  from 
it.  This  radius  of  149,000,000 
kilometers  (93,000,000  miles)  is  in- 
deed, as  previously  observed,  the 
unit,  the  meter  of  celestial  meas- 
ures. The  angle  is  of  course  smaller 
in  proportion  as  the  star  is  more 
distant,  and  the  apparent  motion 
of  the  star  diminishes  in  the  same 
proportion.  But  the  stars  are  all 
so  distant  that  their  annual  dis- 
placement of  perspective  is  almost 
imperceptible,  and  very  exact  in- 
struments are  required  for  its  de- 
tection. 

The  researches  of  the  astrono- 
mers have  proved  that  there  is  not 
scribed  by  the  stars     one  star  for  which  the  parallax  is 

as  a  result  of  the  .         .          -          .  . 
f   ,.    .  equal  to  that  of  another.    The  mi- 
annual  displace- 
ment of  the  Earth,  nuteness  of  this  angle,  and  the  ex- 

306 


FIG.  84. — Small   ap- 
parent ellipses  de- 


ON  METHODS 

traordinary  difficulties  experienced  in  measuring  the 
distance  of  the  stars,  will  be  appreciated  from  the  fact 
that  the  value  of  a  second  is  so  small  that  the  displace- 
ment of  any  star  corresponding  with  it  could  be  covered 
by  a  spider's  thread. 

A  second  of  arc  corresponds  to  the  size  of  an  ob- 
ject at  a  distance  of  206,265  times  its  diameter;  to  a 
millimeter  seen  at  206  meters'  distance;  to  a  hair,  TV  of  a 
millimeter  in  thickness,  at  20  meters'  distance  (more  in- 
visible to  the  naked  eye).  And  yet  this  value  is  in  excess 
of  those  actually  obtained.  In  fact: — the  apparent  dis- 
placement of  the  nearest  star  is  calculated  at  TVir  °f  a 
second  (o".75),  i  *.,  from  this  star,  a  of  Centaur,  the 
half-diameter  of  the  terrestrial  orbit  is  reduced  to  this 
infinitesimal  dimension.  Now  in  order  that  the  length 
of  any  straight  line  seen  from  the  front  be  reduced  until 
it  appear  to  subtend  no  more  than  an  angle  of  o".75,  it 
must  be  removed  to  a  distance  275,000  times  its  length. 
As  the  radius  of  the  terrestrial  orbit  is  149,000,000  kilo- 
meters (93,000,000  miles),  the  distance  which  separates 
a  ot  Centaur  from  our  world  must  therefore  =  41,000,- 
000,000,000  kilometers  (25,000,000,000,000  miles).  And 
that  is  the  nearest  star.  We  saw  in  Chapter  II  that  it 
shines  in  the  southern  hemisphere.  The  next,  and  one 
that  can  be  seen  in  our  latitudes,  is  6 1  of  Cygnus,  which 
floats  in  the  Heavens  68,000,000,000,000  kilometers 
21  307 


ASTRONOMY  FOR  AMATEURS 

(42,000,000,000,000  miles)  from  here.  This  little  star, 
of  fifth  magnitude,  was  the  first  of  which  the  distance 
was  determined  (by  Bessel,  1837-1840). 

All  the  rest  are  much  more  remote,  and  the  proces- 
sion is  extended  to  infinity, 

We  can  not  conceive  directly  of  such  distances,  and 
in  order  to  imagine  them  we  must  again  measure  space 
by  time. 

In  order  to  cover  the  distance  that  separates  us  from 
our  neighbor,  a  of  Centaur,  light,  the  most  rapid  of  all 
couriers,  takes  4  years,  128  days.  If  we  would  follow  it, 
we  must  not  jump  from  start  to  finish,  for  that  would 
not  give  us  the  faintest  idea  of  the  distance:  we  must  take 
the  trouble  to  think  out  the  direct  advance  of  the  ray  of 
light,  and  associate  ourselves  with  its  progress.  We 
must  see  it  traverse  300,000  kilometers  (186,000  miles) 
during  the  first  second  of  the  journey;  then  300,000  more 
in  the  second,  which  makes  600,000  kilometers;  then  once 
more  300,000  kilometers  during  the  third,  and  so  on 
without  stopping  for  four  years  and  four  months.  If  we 
take  this  trouble  we  may  realize  the  value  of  the  figure; 
otherwise,  as  this  number  surpasses  all  that  we  are  in 
the  habit  of  realizing,  it  will  have  no  significance  for  us, 
and  will  be  a  dead  letter. 

If  some  appalling  explosion  occurred  in  this  star,  and 
the  sound  in  its  flight  of  340  meters  (1,115  ^eet)  Per 

308 


ON  METHODS 

second  were  able  to  cross  the  void  that  separates  us  from 
it,  the  noise  of  this  explosion  would  only  reach  us  in 
3,000,000  years. 

A  train  started  at  a  speed  of  1 06  kilometers 
(65  miles)  per  hour  would  have  to  run  for  46,000,000 
years,  in  order  to  reach  this  star,  our  neighbor  in  the 
celestial  kingdom. 

The  distance  of  some  thirty  of  the  stars  has  been 
determined,  but  the  results  arc  dubious. 

The  dazzling  Sinus  reigns  Q2,ooo,ooo,ooo  kilo- 
meters (57,000,000/300  miles),  the  pale  Vega  at  204,- 
000,000,000.  Each  of  these  magnificent  stars  must  be  a 
huge  sun  to  burn  at  such  a  distance  with  such  luminosity. 
Some  are  millions  of  times  larger  than  the  Earth.  Most 
of  them  are  more  voluminous  than  our  Sun.  On  all 
sides  they  scintillate  at  inaccessible  distances,  and  their 
light  strays  a  long  while  in  space  before  it  encounters 
the  Earth.  The  luminous  ray  that  we  receive  to-day 
from  some  pale  star  hardly  perceptible  to  our  eyes— 
so  enormous  is  its  distance — may  perhaps  bring  us 
the  last  emanation  of  a  sun  that  expired  thousands  of 
years  ago. 

If  these  methods  have  been  clear  to  my  readers, 
they  may  also  be  interested  perhaps  in  knowing  the 
means  employed  in  weighing  the  worlds.  The  process 

309 


ASTRONOMY  FOR  AMATEURS 

is  as  simple  and  as  clear  as  those  of  which  we  have 
been  speaking. 

Weighing  the  stars!  Such  a  pretension  seems 
Utopian,  and  one  asks  oneself  curiously  what  sort 
of  balance  the  astronomers  must  have  adopted  in 
order  to  calculate  the  weight  of  Sun,  Moon,  planets 
or  stars. 

Here,  figures  replace  weights.  Ladies  proverbially 
dislike  figures:  yet  it  would  be  easier  for  some  society 
dame  to  weigh  the  Sun  at  the  point  of  her  pen,  by  writing 
down  a  few  columns  of  figures  with  a  little  care,  than 
to  weigh  a  12  kilogram  case  of  fruit,  or  a  dress-basket 
of  35  kilos,  by  direct  methods. 

Weighing  the  Sun  is  an  amusement  like  any  other, 
and  a  change  of  occupation. 

If  the  Moon  were  not  attracted  by  the  Earth,  she 
would  glide  through  the  Heavens  along  an  indefinite 
straight  line,  escaping  at  the  tangent.  But  in  virtue  of 
the  attraction  that  governs  the  movements  of  all  the 
Heavenly  bodies,  our  satellite  at  a  distance  of  60  times 
the  terrestrial  half-diameter  revolves  round  us  in 
27  days,  7  hours,  43  minutes,  nj  seconds,  continually 
leaving  the  straight  line  to  approach  the  Earth,  and 
describing  an  almost  circular  orbit  in  space.  If  at  any 
moment  we  trace  an  arc  of  the  lunar  orbit,  and  if  a 
tangent  is  taken  to  this  arc,  the  deviation  from  the 

310 


ON  METHODS 

straight  line  caused  by  the  attraction  of  our  planet  is 
found  to  be  I J  millimeter  per  second. 

This  is  the  quantity  by  which  the  Moon  drops 
toward  us  in  each  second,  during  which  she  accom- 
plishes 1,017  meters  of  her  orbit. 

On  the  other  hand,  no  body  can  fall  unless  it  be 
attracted,  drawn  by  another  body  of  a  more  powerful 
mass. 

Beings,  animals,  objects,  adhere  to  the  soil,  and 
weigh  upon  the  Earth,  because  they  are  constantly 
attracted  to  it  by  an  irresistible  force. 

Weight  and  universal  attraction  are  one  and  the 
same  force. 

On  the  other  hand,  it  can  be  determined  that  if  an 
object  is  left  to  itself  upon  the  surface  of  the  Earth,  it 
drops  4.90  meters  during  the  first  second  of  its  fall. 

We  also  know  that  attraction  diminishes  with  the 
square  of  the  distance,  and  that  if  we  could  raise  a  stone 
to  the  height  of  the  Moon,  and  then  abandon  it  to  the 
attraction  of  our  planet,  it  would  in  the  first  second  fall 
4.90  meters  divided  by  the  square  of  60,  or  3,600 — that 
is,  of  I J  millimeters,  exactly  the  quantity  by  which  the 
Moon  deviates  from  the  straight  line  she  would  pursue 
if  the  Earth  were  not  influencing  her. 

The  reasoning  just  stated  for  the  Moon  is  equally 
applicable  to  the  Sun. 

3" 


ASTRONOMY  FOR  AMATEURS 

The  distance  of  the  Sun  is  23,386  times  the  radius 
of  the  Earth.  In  order  to  know  how  much  the  intensity 
of  terrestrial  weight  would  be  diminished  at  such  a  dis- 
tance, we  should  look,  in  the  first  place,  for  the  square 
of  the  number  representing  the  distance — that  15,23,386 
multiplied  by  itself,  =  546,905,000.  If  we  divide  4.90 
meters,  which  represents  the  attractive  force  of  our 
planet,  by  this  number,  we  get  TmrfFTTOT  °f  a  millimeter, 
and  we  see  that  at  the  distance  of  the  Sun,  the  Earth's 
attraction  would  really  be  almost  nil. 

Now  let  us  do  for  our  planet  what  we  did  for  its 
satellite.  Let  us  trace  the  annual  orbit  of  the  terres- 
trial globe  round  the  central  orb,  and  we  shall  find  that 
the  Earth  falls  in  each  second  2.9  millimeters  toward 
the  Sun. 

This  proportion  gives  the  attractive  force  of  the 
Sun  in  relation  to  that  of  the  Earth,  and  proves  that  the 
Sun  is  324,000  times  more  powerful  than  our  world, 
for  2.9  millimeters  divided  by  0.000,009  equals  324,000, 
if  worked  out  into  the  ultimate  fractions  neglected  here 
for  the  sake  of  simplicity. 

A  great  number  of  stars  have  been  weighed  by  the 
same  method. 

Their  mass  is  estimated  by  the  movement  of  a 
satellite  round  them,  and  it  is  by  this  method  that  we 
are  able  to  affirm  that  Jupiter  is  310  times  heavier  than 

312 


ON  METHODS 

the  Earth,  Saturn  92  times,  Neptune  16  times,  Uranus 
14  times,  while  Mars  is  much  less  heavy,  its  weight  being 
only  two-thirds  that  of  our  own. 

The  planets  which  have  no  satellites  have  been 
weighed  by  the  perturbations  which  they  cause  in  other 
stars,  or  ia  the  imprudent  comets  that  sometimes  tarry 
in  their  vicinity.  Mercury  weighs  very  much  less  than 
the  Earth  (only  J-^Q")  and  Venus  about  y%.  So  the 
beautiful  star  of  the  evening  and  morning  is  not  so 
light  as  her  name  might  imply,  and  there  is  no  great  dif- 
ference between  her  weight  and  our  own. 

As  the  Moon  has  no  secondary  body  submitted  to 
her  influence,  her  weight  has  been  calculated  by  reckon- 
ing the  amount  of  water  she  attracts  at  each  tide  in 
the  ocean,  or  by  observing  the  effects  of  her  attraction  on 
the  terrestrial  globe.  When  the  Moon  is  before  us,  in 
the  last  quarter,  she  makes  us  travel  faster,  whereas 
in  the  first  quarter,  when  she  is  behind,  she  delays  us. 

All  the  calculations  agree  in  showing  us  that  the  orb 
of  night  is  8 1  times  less  heavy  than  our  planet.  There 
is  nearly  as  much  difference  in  weight  between  the  Earth 
and  the  Moon  as  between  an  orange  and  a  grape. 

Not  content  with  weighing  the  planets  of  our  system, 
astronomers  have  investigated  the  weight  of  the  stars. 
How  have  they  been  enabled  to  ascertain  the  quantity 


ASTRONOMY  FOR  AMATEURS 

of  matter  which  constitutes  these  distant  Suns — incan- 
descent globes  of  fire  scattered  in  the  depths  of  space  ? 

They  have  resorted  to  the  same  method,  and  it  is  by 
the  study  of  the  attractive  influence  of  a  sun  upon  some 
other  contiguous  neighboring  star,  that  the  weight  of  a 
few  of  these  has  been  calculated. 

Of  course  this  method  can  only  be  applied  to  those 
double  stars  of  which  the  distance  is  known. 

It  has  been  discovered  that  some  of  the  tiny  stars 
that  we  can  hardly  see  twinkling  in  the  depths  of  the 
azure  sky  are  enormous  suns,  larger  and  heavier  than 
our  own,  and  millions  of  times  more  voluminous  than 
the  Earth. 

Our  planet  is  only  a  grain  of  dust  floating  in  the 
immensity  of  Heaven.  Yet  this  atom  of  infinity  is  the 
cradle  of  an  immense  creation  incessantly  renewed,  and 
perpetually  transformed  by  the  accumulated  centuries. 

And  what  diversity  exists  in  this  army  of  worlds  and 
suns,  whose  regular  harmonious  march  obeys  a  mute 
order.  .  . 

But  we  have  as  yet  said  nothing  about  weight  on  the 
surface  of  the  worlds,  and  I  see  signs  of  impatience  in 
my  readers,  for  after  so  much  simple  if  unpoetical  demon- 
stration, they  will  certainly  ask  me  for  the  explanation 
that  will  prove  to  them  that  a  kilogram  transported  to 
Jupiter  or  Mars  would  weigh  more  or  less  than  here. 

314 


ON  METHODS 

Give  me  your  attention  five  minutes  longer,  and  I  will 
restore  your  faith  in  the  astronomers. 

It  must  not  be  supposed  that  objects  at  the  surface 
of  a  world  like  Jupiter,  310  times  heavier  than  our  own, 
weigh  310  times  more.  That  would  be  a  serious  error. 
In  that  case  we  should  have  to  assume  that  a  kilogram 
transported  to  the  surface  of  the  Sun  would  there  weigh 
324,000  times  more,  or  324,000  kilograms.  That  would 
be  correct  if  these  orbs  were  of  the  same  dimensions  as 
the  Earth.  But  to  speak,  for  instance,  only  of  the  divine 
Sun,  we  know  that  he  is  108  times  larger  than  our  little 
planet. 

Now,  weight  at  the  surface  of  a  celestial  body  depends 
not  only  on  its  mass,  but  also  on  its  diameter. 

In  order  to  know  the  weight  of  any  body  upon  the 
surface  of  the  Sun,  we  must  argue  as  follows: 

Since  a  body  placed  upon  the  surface  of  the  Sun  is 
108  times  farther  from  its  center  than  it  is  upon  a  globe 
of  the  dimensions  of  the  Earth,  and  since,  on  the  other 
hand,  attraction  diminishes  with  the  square  of  the  dis- 
tance, the  intensity  of  the  weight  would  there  be  108 
multiplied  by  108,  or  11,700  times  weaker.  Now  divide 
the  number  representing  the  mass,  /.  e.,  324,000,  by  this 
number  11,700,  and  it  results  that  bodies  at  the  surface 
of  the  Sun  are  28  times  heavier  than  here.  A  woman 
whose  weight  was  60  kilos  would  weigh  1,680  kilograms 


ASTRONOMY  FOR  AMATEURS 

there  if  organized  in  the  same  way  as  on  the  Earth,  and 
would  find  walking  very  difficult,  for  at  each  step  she 
would  lift  up  a  shoe  that  weighed  at  least  ten  kilograms. 

This  reasoning  as  just  stated  for  the  Sun  may  be  ap- 
plied to  the  other  stars.  We  know  that  on  the  surface 
of  Jupiter  the  intensity  of  weight  is  twice  and  a  third 
times  as  great  as  here,  while  on  Mars  it  only  equals  -fjfo. 

On  the  surface  of  Mercury,  weight  is  nearly  twice  as 
small  again  as  here.  On  Neptune  it  is  approximately 
equal  to  our  own. 

With  deference  to  the  Selenites,  everything  is  at  its 
lightest  on  the  Moon:  a  man  weighing  70  kilograms  on 
the  Earth  would  not  weigh  more  than  12  kilos  there. 

So  all  tastes  can  be  provided  for:  the  only  thing  to  be 
regretted  is  that  one  can  not  choose  one's  planet  with 
fcJbe  same  facility  as  one's  residence  upon  the  Earth. 


316 


CHAPTER   XII 
LIFE,   UNIVERSAL   AND    ETERNAL 

AND  now,  while  thanking  my  readers  for  having 
followed  me  so  far  in  this  descriptive  account  of  the 
marvels  of  the  Cosmos,  I  must  inquire  what  philosoph- 
ical impression  has  been  produced  on  their  minds  by 
these  celestial  excursions  to  the  other  worlds  ?  Are 
you  left  indifferent  to  the  pageant  of  the  Heavens  ? 
When  your  imagination  was  borne  away  to  these  distant 
stars,  suns  of  the  infinite,  these  innumerable  stellar 
systems  disseminated  through  a  boundless  eternity,  did 
you  ask  what  existed  there,  what  purpose  was  served  by 
those  dazzling  spheres,  what  effects  resulted  from  these 
forces,  radiations,  energies  ?  Did  you  reflect  that  the 
elements  which  upon  our  little  Earth  determined  a  vital 
activity  so  prodigious  and  so  varied  must  needs  have 
spread  the  waves  of  an  incomparably  vaster  and  more 
diversified  existence  throughout  the  immensities  of  the 
Universe  ?  Have  you  felt  that  all  can  not  be  dead  and 
deserted,  as  we  are  tempted  by  the  illusions  of  our  ter- 
restrial senses  and  of  our  isolation  to  believe  in  the 
silence  of  the  night:  that  on  the  contrary,  the  real  aim  of 

317 


ASTRONOMY  FOR  AMATEURS 

Astronomy,  instead  of  ending  with  statements  of  the 
positions  and  movements  of  the  stars,  is  to  enable  us  to 
penetrate  to  them,  to  make  us  divine,  and  know,  and 
appreciate  their  physical  constitution,  their  degree  of 
life  and  intellectuality  in  the  universal  order  ? 

On  the  Earth,  it  is  Life  and  Thought  that  flourish; 
and  it  is  Life  and  Thought  that  we  seek  again  in  these 
starry  constellations  strewn  to  Infinitude  amid  the  im- 
measurable fields  of  Heaven. 

The  humble  little  planet  that  we  inhabit  presents 
itself  to  us  as  a  brimming  cup,  overflowing  at  every 
outlet.  Life  is  everywhere.  From  the  bottom  of  the 
seas,  from  the  valleys  to  the  mountains,  from  the  vege- 
tation that  carpets  the  soil,  from  the  mold  in  the  fields 
and  woods,  from  the  air  we  breathe,  arises  an  immense, 
prodigious,  and  perpetual  murmur.  Listen!  it  is  the 
great  voice  of  Nature,  the  sum  of  all  the  unknown  and 
mysterious  voices  that  are  forever  calling  to  us,  from 
the  ocean  waves,  from  the  forest  winds,  from  the  300,000 
kinds  of  insects  that  are  redundant  everywhere,  and 
make  a  lively  community  on  the  surface  of  our  globe.  A 
drop  of  water  contains  thousands  of  curious  and  agile 
creatures.  A  grain  of  dust  from  the  streets  of  Paris  is 
the  home  of  130,000  bacteria.  If  we  turn  over  the  soil  of 
a  garden,  field,  or  meadow,  we  find  the  earthworms  work- 
ing to  produce  assimilable  slime.  If  we  lift  a  stone  in  the 

318 


LIFE,  UNIVERSAL  AND  ETERNAL 

path,  we  discover  a  crawling  population.  If  we  gather 
a  flower,  detach  a  leaf,  we  everywhere  find  little  insects 
living  a  parasitic  existence.  Swarms  of  midges  fly  in 
the  sun,  the  trees  of  the  wood  are  peopled  with  nests, 
the  birds  sing,  and  chase  each  other  at  play,  the  lizards 
dart  away  at  our  approach,  we  trample  down  the  ant- 
heaps  and  the  molehills.  Life  enwraps  us  in  an  inex- 
orable encroachment  of  which  we  are  at  once  the  heroes 
and  the  victims,  perpetuating  itself  to  its  own  detriment, 
as  imposed  upon  it  by  an  eternal  reproduction.  And 
this  from  all  time,  for  the  very  stones  of  which  we  build 
our  houses  are  full  of  fossils  so  prodigiously  multiplied 
that  one  gram  of  such  stone  will  often  contain  millions 
of  shells,  marvels  of  geometrical  perfection.  The  in- 
finitely little  is  equal  to  the  infinitely  great. 

Life  appears  to  us  as  a  fatal  law,  an  imperious  force 
which  all  obey,  as  the  result  and  the  aim  of  the  associa- 
tion of  atoms.  This  is  illustrated  for  us  upon  the  Earth, 
our  only  field  of  direct  observation.  We  must  needs  be 
blind  not  to  see  this  spectacle,  deaf  not  to  hear  its 
reaching.  On  what  pretext  could  one  suppose  that  our 
little  globe  which,  as  we  have  seen,  has  received  no 
privileges  from  Nature,  is  the  exception;  and  that  the 
entire  Universe,  save  for  one  insignificant  isle,  is  devoted 
to  vacancy,  solitude,  and  death  ? 

We  have  a  tendency  to  imagine  that  Life  can  not  exist 
319 


ASTRONOMY  FOR  AMATEURS 

under  conditions  other  than  terrestrial,  and  that  the 
other  worlds  can  only  be  inhabited  on  the  condition 
of  being  similar  to  our  own.  But  terrestrial  nature  itself 
demonstrates  to  us  the  error  of  this  way  of  thinking. 
We  die  in  the  water:  fishes  die  out  of  the  water.  Again, 
short-sighted  naturalists  affirm  categorically  that  Life 
is  impossible  at  the  bottom  of  the  sea:  I,  because  it  is 
in  complete  darkness;  2,  because  the  terrible  pressure 
would  burst  any  organism ;  3,  because  all  motion  would 
be  impossible  there,  and  so  on.  Some  inquisitive  person 
sends  down  a  dredge,  and  brings  up  lovely  creatures,  so 
delicate  in  structure  that  the  daintiest  touch  must  proceed 
with  circumspection.  There  is  no  light  in  these  depths: 
they  make  it  with  their  own  phosphorescence.  Other 
inquirers  visit  subterranean  caverns,  and  discover  ani- 
mals and  plants  whose  organs  have  been  transformed  by 
adaptation  to  their  gloomy  environment. 

What  right  have  we  to  say  to  the  vital  energy  that 
radiates  round  every  Sun  of  the  Universe:  "Thus  far 
shalt  thou  come,  and  no  further"?  In  the  name  of 
Science  ?  An  absolute  mistake.  The  Known  is  an  in- 
finitesimal island  in  the  midst  of  the  vast  ocean  of  the 
Unknown.  The  deep  seas  which  seemed  to  be  a  barrier 
are,  as  we  have  seen,  peopled  with  special  life.  Some 
one  objects:  But  after  all,  there  is  air  there,  there  is  oxy- 
gen: oxygen  is  indispensable:  a  world  without  oxygen 

320 


LIFE,  UNIVERSAL  AND  ETERNAL 

would  be  a  world  of  death,  an  eternally  sterile  desert. 
Why  ?  Because  we  have  not  yet  come  across  beings 
that  can  breathe  without  air,  and  live  without  oxygen  ? 
Another  mistake.  Even  if  we  did  not  know  of  any,  it 
would  not  prove  that  they  do  not  exist.  But  as  it  hap- 
pens, we  do  know  of  such:  the  anarobia.  These  beings 
live  without  air,  without  oxygen.  Better  still:  oxygen 
kills  them! 

All  the  evidence  goes  to  show  that  in  interpreting 
as  we  ought  the  spectacle  of  terrestrial  life,  and  the  posi- 
tive facts  acquired  by  Science,  we  should  enlarge  the 
circle  of  our  conceptions  and  our  judgments,  and  not 
limit  extra-terrestrial  existence  to  the  servile  image  of 
what  is  in  existence  here  below.  Terrestrial  organic 
forms  are  due  to  local  causes  upon  our  planet.  The 
chemical  constitution  of  water  and  of  the  atmosphere, 
temperature,  light,  density,  weight,  are  so  many  elements 
that  have  gone  to  form  our  bodies.  Our  flesh  is  com- 
posed of  carbon,  nitrogen,  hydrogen,  and  oxygen  com- 
bined in  the  state  of  water,  and  of  some  other  elements, 
among  which  we  may  instance  sodium  chloride  (salt). 
The  flesh  of  animals  is  not  chemically  different  from  our 
own.  All  this  comes  from  the  water  and  the  air,  and 
returns  to  them  again.  The  same  elements,  in  very 
minute  quantities,  make  up  all  living  bodies.  The  ox 
that  browses  on  the  grass  is  formed  of  the  same  flesh 

32I 


ASTRONOMY  FOR  AMATEURS 

as  the  man  who  eats  the  beef.  All  organized  terrestrial 
matter  is  only  carbon  combined  in  variable  proportions 
with  hydrogen,  nitrogen,  oxygen,  etc. 

But  we  have  no  right  to  forbid  Nature  to  act  differ- 
ently in  worlds  from  which  carbon  is  absent.  A  world, 
for  example,  in  which  silica  replaces  carbon,  silicic  acid 
carbonic  acid,  might  be  inhabited  by  organisms  abso- 
lutely different  from  those  which  exist  on  the  Earth, 
different  not  only  in  form,  but  also  in  substance.  We 
already  know  stars  and  suns  for  which  spectral  analysis 
reveals  a  predominance  of  silica,  e.  g.,  Rigel  and  Deneb. 
In  a  world  where  chlorine  predominated,  we  might 
expect  to  find  hydrochloric  acid,  and  all  the  fecund 
family  of  chlorides,  playing  an  important  part  in  the 
phenomena  of  life.  Might  not  bromine  be  associated 
in  other  formations  ?  Why,  indeed,  should  we  draw  the 
line  at  terrestrial  chemistry  ?  What  is  to  prove  that 
these  elements  are  really  simple  ?  May  not  hydrogen, 
carbon,  oxygen,  nitrogen,  and  sulphur  all  be  compounds  ? 
Their  equivalents  are  multiples  of  the  first:  I,  6,  8,  14, 
16.  And  is  even  hydrogen  the  most  simple  of  the 
elements  ?  Is  not  its  molecule  composed  of  atoms,  and 
may  there  not  exist  a  single  species  of  primitive  atom, 
whose  geometric  arrangement  and  various  associations 
might  constitute  the  molecules  of  the  so-called  simple 
elements  ? 

322 


LIFE,  UNIVERSAL  AND  ETERNAL 

In  our  own  solar  system  we  discover  the  essential 
differences  between  certain  planets.  In  the  spectrum 
of  Jupiter,  for  instance,  we  are  aware  of  the  action  of  an 
unknown  substance  that  manifests  itself  by  a  marked 
absorption  of  certain  red  rays.  This  gas,  which  does  not 
exist  upon  the  Earth,  is  seen  still  more  obviously  in  the 
atmospheres  of  Saturn  and  Uranus.  Indeed,  upon  this 
last  planet  the  atmosphere  appears,  apart  from  its  water 
vapor,  to  have  no  sort  of  analogy  with  our  own.  And 
in  the  solar  spectrum  itself,  many  of  the  lines  have  not 
yet  been  identified  with  terrestrial  substances. 

The  interrelation  of  the  planets  is  of  course  incon- 
trovertible, since  they  are  all  children  of  the  same  parent. 
But  they  differ  among  themselves,  not  merely  in  respect 
of  situation,  position,  volume,  mass,  density,  temperature, 
atmosphere,  but  again  in  physical  and  chemical  con- 
stitution. And  the  point  we  would  now  accent  is  that 
this  diversity  should  not  be  regarded  as  an  obstacle 
to  the  manifestations  of  life,  but,  on  the  contrary,  as 
a  new  field  open  to  the  infinite  fecundity  of  the  uni- 
versal mother. 

When  our  thoughts  take  wing,  not  only  to  our  neigh- 
bors, Moon,  Venus,  Mars,  Jupiter,  or  Saturn,  but  still 
more  toward  the  myriads  of  unknown  worlds  that 
gravitate  round  the  suns  disseminated  in  space,  we  have 
no  plausible  reason  for  imagining  that  the  inhabitants 
22  323 


ASTRONOMY  FOR  AMATEURS 

of  these  other  worlds  of  Heaven  resemble  us  in  any  way, 
whether  in  form,  or  even  in  organic  substance. 

The  substance  of  the  terrestrial  human  body  is  due 
to  the  elements  of  our  planet,  and  notably  to  carbon. 
The  terrestrial  human  form  derives  from  the  ancestral 
animal  forms  to  which  it  has  gradually  raised  itself  by 
the  continuous  progress  of  the  transformation  of  species. 
To  us  it  seems  obvious  that  we  are  man  or  woman,  be- 
cause we  have  a  head,  a  heart,  lungs,  two  legs,  two  arms, 
and  so  on.  Nothing  is  less  a  matter  of  course.  That 
we  are  constituted  as  we  are,  is  simply  the  result  of  our 
pro-simian  ancestors  having  also  had  a  head,  a  heart, 
lungs,  legs,  and  arms — less  elegant  than  your  own,  it  is 
true,  Madam,  but  still  of  the  same  anatomy.  And 
more  and  more,  by  the  progress  of  paleontology,  we  are 
delving  down  to  the  origin  of  beings.  As  certain  as  it  is 
that  the  bird  derives  from  the  reptile  by  a  process  of  or- 
ganic evolution,  so  certain  is  it  that  terrestrial  Humanity 
represents  the  topmost  branches  of  the  huge  genealogical 
tree,  whereof  all  the  limbs  are  brothers,  and  the  roots  of 
which  are  plunged  into  the  very  rudiments  of  the  most 
elementary  and  primitive  organisms. 

The  multitude  of  worlds  is  surely  peopled  by  every 
imaginable  and  unimaginable  form.  Terrestrial  man 
is  endowed  with  five  senses,  or  perhaps  it  is  better  to  say 
six.  Why  should  Nature  stop  at  this  point  ?  Why,  for 

324 


LIFE,  UNIVERSAL  AND  ETERNAL 

instance,  may  she  not  have  given  to  certain  beings  an 
electrical  sense,  a  magnetic  sense,  a  sense  of  orientation, 
an  organ  able  to  perceive  the  ethereal  vibrations  of  the 
infra-red  or  ultra-violet,  or  permitted  them  to  hear  at  a 
distance,  or  to  see  through  walls  ?  We  eat  and  digest 
like  coarse  animals,  we  are  slaves  to  our  digestive  tube: 
may  there  not  be  worlds  in  which  a  nutritive  atmosphere 
enables  its  fortunate  inhabitants  to  dispense  with  this 
absurd  process  ?  The  least  sparrow,  even  the  dusky 
bat,  has  an  advantage  over  us  in  that  it  can  fly  through 
the  air.  Think  how  inferior  are  our  conditions,  since 
the  man  of  greatest  genius,  the  most  exquisite  woman, 
are  nailed  to  the  soil  like  any  vulgar  caterpillar  before 
its  metamorphosis!  Would  it  be  a  disadvantage  to  in- 
habit a  world  in  which  we  might  fly  whither  we  would; 
a  world  of  scented  luxury,  full  of  animated  flowers;  a 
world  where  the  winds  would  be  incapable  of  exciting 
a  tempest,  where  several  suns  of  different  colors — the 
diamond  glowing  with  the  ruby,  or  the  emerald  with  the 
sapphire — would  burn  night  and  day  (azure  nights  and 
scarlet  days)  in  the  glory  of  an  eternal  spring;  with 
multi-colored  moons  sleeping  in  the  mirror  of  the  wa- 
ters, phosphorescent  mountains,  aerial  inhabitants, — 
men,  women,  or  perhaps  of  other  sexes, — perfect  in 
their  forms,  gifted  with  multiple  sensibilities,  luminous 
at  will,  incombustible  as  asbestos,  perhaps  immortal, 

325 


ASTRONOMY  FOR  AMATEURS 

unless  they  commit  suicide  out  of  curiosity  ?  Lilliputian 
atoms  as  we  are,  let  us  once  for  all  be  convinced  that 
our  imagination  is  but  sterility,  in  the  midst  of  an  in- 
finitude hardly  glimpsed  by  the  telescope. 

One  important  point  seems  always  to  be  ignored 
expressly  by  those  who  blindly  deny  the  doctrine  of  the 
plurality  of  worlds.  It  is  that  this  doctrine  does  not 
apply  more  particularly  to  the  present  epoch  than  to 
any  other.  Our  time  is  of  no  importance,  no  absolute 
value.  Eternity  is  the  field  of  the  Eternal  Sower.  There 
is  no  reason  why  the  other  worlds  should  be  inhabited 
now  more  than  at  any  other  epoch. 

What,  indeed,  is  the  Present  Moment  ?  It  is  an  open 
trap  through  which  the  Future  falls  incessantly  into  the 
gulf  of  the  Past. 

The  immensity  of  Heaven  bears  in  its  bosom  cradles 
as  well  as  tombs,  worlds  to  come  and  perished  worlds. 
It  abounds  in  extinct  suns,  and  cemeteries.  In  all 
probability  Jupiter  is  not  yet  inhabited.  What  does  this 
prove  ?  The  Earth  was  not  inhabited  during  its  primor- 
dial period:  what  did  that  prove  to  the  inhabitants  of 
Mars  or  of  the  Moon,  who  were  perhaps  observing  it  at 
that  epoch,  a  few  million  years  ago  ? 

To  pretend  that  our  globe  must  be  the  only  inhab- 
ited world  because  the  others  do  not  resemble  it,  is  to 
reason,  not  like  a  philosopher,  but,  as  we  remarked 

326 


LIFE,  UNIVERSAL  AND  ETERNAL 

before,  like  a  fish.  Every  rational  fish  ought  to  assume 
that  it  is  impossible  to  live  out  of  water,  since  its  outlook 
and  its  philosophy  do  not  extend  beyond  its  daily  life. 
There  is  no  answer  to  this  order  of  reasoning,  except 
to  advise  a  little  wider  perception,  and  extension  of  the 
too  narrow  horizon  of  habitual  ideas. 

For  us  the  resources  of  Nature  may  be  considered 
infinite,  and  "positive"  science,  founded  upon  our  senses 
only,  is  altogether  inadequate,  although  it  is  the  only 
possible  basis  of  our  reasoning.  We  must  learn  to  see 
with  the  eyes  of  our  spirit. 

As  to  the  planetary  systems  other  than  our  own,  we 
are  no  longer  reduced  to  hypotheses.  We  already  know 
with  certainty  that  our  Sun  is  no  exception,  as  was  sug- 
gested, and  is  still  maintained,  by  some  theorists.  The 
discovery  in  itself  is  curious  enough. 

It  is  surely  an  exceptional  situation  that,  given  a  si- 
dereal system  composed  of  a  central  sun,  and  of  one  or 
more  stars  gravitating  round  him,  the  plane  of  such  a 
system  should  fall  just  within  our  line  of  vision,  and 
that  it  should  revolve  in  such  a  way  that  the  globes  of 
which  it  is  composed  pass  exactly  between  this  sun  and 
ourselves  in  turning  round  him,  eclipsing  him  more  or 
less  during  this  transit.  As,  on  the  other  hand,  the 
eclipses  would  be  our  only  means  of  determining  the 
existence  of  these  unknown  planets  (save  indeed  from 

327 


ASTRONOMY  FOR  AMATEURS 

perturbation,  as  in  the  case  of  Sirius  and  Procyon),  it 
might  have  seemed  quixotic  to  hope  for  like  conditions 
in  order  to  discover  solar  systems  other  than  our  own. 
But  these  exceptional  circumstances  have  reproduced 
themselves  at  different  parts  of  the  Heavens. 

Thus,  for  instance,  we  have  seen  that  the  variable 
star  Algol  owes  its  variations  in  brilliancy,  which  reduce 
it  from  second  to  fourth  magnitude  every  sixty-nine 
hours,  to  the  interposition  of  a  body  between  itself  and 
the  Earth,  and  celestial  mechanics  has  already  been 
able  to  determine  accurately  the  orbit  of  this  body,  its 
dimensions  and  its  mass,  and  even  the  flattening  of  the 
sun  Algol.  Here,  then,  is  a  system  in  which  We  know 
the  sun  and  an  enormous  planet,  whose  revolution  is 
effected  in  sixty-nine  hours  with  extreme  rapidity,  as 
measured  by  the  spectroscope. 

The  star  d  of  Cepheus  is  in  the  same  case:  it  is  an  orb 
eclipsed  in  a  period  of  129  hours,  and  its  eclipsing  planet 
also  revolves  in  the  plane  of  our  vision.  The  variable 
star  in  Ophiuchus  has  an  analogous  system,  and  obser- 
vation has  already  revealed  a  great  number  of  others. 

Since,  then,  a  certain  number  of  solar  systems  dif- 
fering from  our  own  have  been  revealed,  as  it  were  in 
section,  to  terrestrial  observation,  this  affords  us  suf- 
ficient evidence  of  the  existence  of  an  innumerable 
quantity  of  solar  systems  scattered  through  the  im- 

328 


LIFE,  UNIVERSAL  AND  ETERNAL 

mensities  of  space,  and  we  are  no  longer  reduced  to 
conjecture. 

On  the  other  hand,  analysis  of  the  motions  of  several 
stars,  such  as  Sirius,  Procyon,  Altair,  proves  that  these 
distant  orbs  have  companions, — planets  not  yet  dis- 
covered by  the  telescope,  and  that  perhaps  never  will 
be  discovered,  because  they  are  obscure,  and  lost  in  the 
radiation  of  the  star. 

Some  savants  have  asserted  that  Life  can  not  ger- 
minate if  the  conditions  of  the  environment  differ  too 
much  from  terrestrial  conditions. 

This  hypothesis  is  purely  gratuitous,  and  we  will 
now  discuss  it. 

In  order  to  examine  what  is  happening  on  the  Earth, 
let  us  mount  the  ladder  of  time  for  a  moment,  to  follow 
the  evolutions  of  Nature. 

There  was  an  epoch  when  the  Earth  did  not  exist. 
Our  planet,  the  future  world  of  our  habitation,  slept 
in  the  bosom  of  the  solar  nebula. 

At  last  it  came  to  birth,  this  cherished  Earth,  a  gase- 
ous, luminous  ball,  poor  reflection  of  the  King  of  Orbs, 
its  parent.  Millions  of  years  rolled  by  before  the  con- 
densation and  cooling  of  this  new  globe  were  sufficiently 
transformed  to  permit  life  to  manifest  itself  in  its  most 
rudimentary  aspects. 

329 


ASTRONOMY  FOR  AMATEURS 

The  first  organic  forms  of  the  protoplasm,  the  first 
aggregations  of  cells,  the  protozoons,  the  zoophytes  or 
plant-animals,  the  gelatinous  mussels  of  the  still  warm 
seas,  were  succeeded  by  the  fishes,  then  by  the  reptiles, 
the  birds,  the  mammals,  and  lastly  man,  who  at  present 
occupies  the  top  of  the  genealogical  tree,  and  crowns 
the  animal  kingdom. 

Humanity  is  comparatively  young  upon  the  Earth. 
We  may  attribute  some  thousands  of  centuries  of  exist- 
ence to  it  .  .  .  — and  some  five  years  of  reason! 

The  terrestrial  organisms,  from  the  lowest  up  to  man, 
are  the  resultant  of  the  forces  in  action  at  the  surface  of 
our  planet.  The  earliest  seem  to  have  been  produced 
by  the  combinations  of  carbon  with  hydrogen  and  ni- 
trogen; they  were,  so  to  speak,  without  animation,  save 
for  some  very  rudimentary  sensibility;  the  sponges, 
corals,  polyps,  and  medusae,  give  us  a  notion  of  these 
primitive  beings.  They  were  formed  in  the  tepid  waters 
of  the  primary  epoch.  As  long  as  there  were  no  con- 
tinents, no  islands  emerging  from  the  level  of  the  uni- 
versal ocean,  there  were  no  beings  breathing  in  the  air. 
The  first  aquatic  creatures  were  succeeded  by  the 
amphibia,  the  reptiles.  Later  on  were  developed  the 
mammals  and  the  birds. 

What,  again,  do  we  not  owe  to  the  plant-world  of  the 
primary  epoch,  of  the  secondary  epoch,  of  the  tertiary 

330 


LIFE,  UNIVERSAL  AND  ETERNAL 

epoch,  which  slowly  prepared  the  good  nutritious  soil 
of  to-day,  in  which  the  roses  flourish,  and  the  peach  and 
strawberry  ripen  ? 

Before  it  gave  birth  to  a  Helen  or  a  Cleopatra,  life 
manifested  itself  under  the  roughest  forms,  and  in  the 
most  varied  conditions.  A  long-period  comet  passing 
in  sight  of  the  Earth  from  time  to  time  would  have  seen 
modifications  of  existence  in  each  of  its  transits,  in 
accordance  with  a  slow  evolution,  corresponding  to  the 
variation  of  the  conditions  of  existence,  and  progressing 
incessantly,  for  if  Life  is  the  goal  of  nature,  Progress  is 
the  supreme  law. 

The  history  of  our  planet  is  the  history  of  life,  with 
all  its  metamorphoses.  It  is  the  same  for  all  the 
worlds,  with  some  exceptions  of  orbs  arrested  in  their 
development. 

The  constitution  of  living  beings  is  in  absolute  rela- 
tion with  the  substances  of  which  they  are  composed,  the 
environment  in  which  they  move,  temperature,  light, 
weight,  density,  the  length  of  day  and  night,  the  sea- 
sons, etc. — in  a  word,  with  all  the  cosmographic  ele- 
ments of  a  world. 

If,  for  example,  we  compare  between  themselves  two 
worlds  such  as  the  Earth  and  Neptune,  utterly  different 
from  the  point  of  view  of  distance  from  the  Sun,  we  could 
not  for  an  instant  suppose  that  organic  structures  could 

331 


ASTRONOMY  FOR  AMATEURS 

have  followed  a  parallel  development  on  these  planets. 
The  average  temperature  must  be  much  lower  on  Nep- 
tune than  on  the  Earth,  and  the  same  holds  for  intensity 
of  light.  The  years  and  seasons  there  are  165  times 
longer  than  with  us,  the  density  of  matter  is  three  times 
as  weak,  and  weight  is,  on  the  contrary,  a  little  greater. 
Under  conditions  so  different  from  our  own,  the  activi- 
ties of  Nature  would  have  to  translate  themselves  un- 
der other  forms.  And  doubtless  the  elementary  bodies 
would  not  be  found  there  in  the  same  proportions.  Con- 
sequently we  have  to  conclude  that  organs  and  senses 
would  not  be  the  same  there  as  here.  The  optic  nerve, 
for  instance,  which  has  formed  and  developed  here  from 
the  rudimentary  organ  of  the  trilobite  to  the  marvels  of 
the  human  eye,  must  be  incomparably  more  sensitive 
upon  Neptune  than  in  our  dazzling  solar  luminosity, 
in  order  to  perceive  radiations  that  we  do  not  perceive 
here.  In  all  probability,  it  is  replaced  there  by  some 
other  organ.  The  lungs,  functioning  there  in  another 
atmosphere,  are  different  from  our  own.  So,  too,  for 
the  stomach  and  digestive  organs.  Corporeal  forms, 
animal  and  human,  can  not  resemble  those  which  exist 
upon  the  Earth. 

Certain  savants  contend  that  if  the  conditions  dif- 
fered too  much  from  terrestrial  conditions,  life  could 
not  be  produced  there  at  all.  Yet  we  have  no  right  to 

332 


LIFE,  UNIVERSAL  AND  ETERNAL 

limit  the  powers  of  Nature  to  the  narrow  bounds  of  our 
sphere  of  observation,  and  to  pretend  that  our  planet 
and  our  Humanity  are  the  type  of  all  the  worlds. 
That  is  a  hypothesis  as  ridiculous  as  it  is  childish. 

Do  not  let  us  be  "  personal,"  like  children,  and  old 
people  who  never  see  beyond  their  room.  Let  us  learn 
to  live  in  the  Infinite  and  the  Eternal. 

From  this  larger  point  of  view,  the  doctrine  of  the 
plurality  of  worlds  is  the  complement  and  the  natural 
crown  of  Astronomy.  What  interests  us  most  in  the 
study  of  the  Universe  is  surely  to  know  what  goes  on 
there. 

These  considerations  show  that,  in  all  the  ages,  what 
really  constitutes  a  planet  is  not  its  skeleton  but  the  life 
that  vibrates  upon  its  surface. 

And  again,  if  we  analyze  things,  we  see  that  for  the 
Procession  of  Nature,  life  is  all,  and  matter  nothing. 

What  has  become  of  our  ancestors,  the  millions  of 
human  beings  who  preceded  us  upon  this  globe  ?  Where 
are  their  bodies  ?  What  is  left  of  them  ?  Search  every- 
where. Nothing  is  left  but  the  molecules  of  air,  water, 
dust,  atoms  of  hydrogen,  nitrogen,  oxygen,  carbon,  etc., 
which  are  incorporated  in  turn  in  the  organism  of  every 
living  being. 

The  whole  Earth  is  a  vast  cemetery,  and  its  finest 

333 


ASTRONOMY  FOR  AMATEURS 

cities  are  rooted  in  the  catacombs.  But  now,  in  crossing 
Paris,  I  passed  for  at  least  the  thousandth  time  near  the 
Church  of  St.  Germain-rAuxerrois,  and  was  obliged 
to  turn  out  of  the  direct  way,  on  account  of  excavations. 
I  looked  down,  and  saw  that  immediately  below  the 
pavement,  they  had  just  uncovered  some  stone  coffins 
still  containing  the  skeletons  that  had  reposed  there  for 
ten  centuries.  From  time  immemorial  the  passers-by  had 
trampled  them  unwittingly  under  foot.  And  I  reflected 
that  it  is  much  the  same  in  every  quarter  of  Paris.  Only 
yesterday,  some  Roman  tombs  and  a  coin  with  the  effigy 
of  Nero  were  found  in  a  garden  near  the  Observatory. 

And  from  the  most  general  standpoint  of  Life,  the 
whole  world  is  in  the  same  case,  and  even  more  so,  seeing 
that  all  that  exists,  all  that  lives,  is  formed  of  elements 
that  have  already  been  incorporated  in  other  beings,  no 
longer  living.  The  roses  that  adorn  the  bosom  of  the 
fair  .  .  .  but  I  will  not  enlarge  upon  this  topic. 

And  you,  so  strong  and  virile,  of  what  elements  is 
your  splendid  body  formed  ?  Where  have  the  elements 
you  absorb  to-day  in  respiration  and  assimilation  been 
drawn  from,  what  lugubrious  adventures  have  they 
been  subject  to  ?  Think  away  from  it:  do  not  insist  on 
this  point:  on  no  account  consider  it.  ... 

And  yet,  let  us  dwell  on  it,  since  this  reality  is  the 
most  evident  demonstration  of  the  ideal;  since  what 

334 


LIFE,  UNIVERSAL  AND  ETERNAL 

exists  is  you,  is  all  of  us,  is  Life',  and  matter  is  only  its 
substance,  like  the  materials  of  a  house,  and  even  less  so, 
since  its  particles  only  pass  rapidly  through  the  frame- 
work of  our  bodies.  A  heap  of  stones  does  not  make 
a  house.  Quintillions  of  tons  of  materials  would  not 
represent  the  Earth  or  any  other  world. 

Yes,  what  really  exists,  what  constitutes  a  complete 
orb,  is  the  city  of  Life.  Let  us  recognize  that  the  flower 
of  life  flourishes  on  the  surface  of  our  planet,  embellishing 
it  with  its  perfume;  that  it  is  just  this  life  that  we  see  and 
admire, — of  which  we  form  part, — and  which  is  the  rai- 
son  d'etre  of  things;  that  matter  floats,  and  crosses,  and 
crosses  back  again,  in  the  web  of  living  beings, — and 
the  reality,  the  goal,  is  not  matter — it  is  the  life  matter 
is  employed  upon. 

Yes,  matter  passes,  and  being  also,  after  sharing  in 
the  concerted  symphony  of  life. 

And  indeed  everything  passes  rapidly! 

What  irrepressible  grief,  what  deep  melancholy, 
what  ineffaceable  regrets  we  feel,  when  as  age  comes  on 
we  look  back,  when  we  see  our  friends  fallen  upon  the 
road  one  after  the  other,  above  all  when  we  visit  the 
beloved  scenes  of  our  childhood,  those  homes  of  other 
years,  that  witnessed  our  first  start  in  terrestrial  exist- 
ence, our  first  games,  our  first  affections — those  affections 
of  childhood  that  seemed  eternal — when  we  wander  over 

335 


ASTRONOMY  FOR  AMATEURS 

those  fields  and  valleys  and  hills,  when  we  see  again  the 
landscape  whose  aspect  has  hardly  changed,  and  whose 
image  is  so  intimately  linked  with  our  first  impres- 
sions. There  near  this  fireside  the  grandfather  danced 
us  on  his  knee,  and  told  us  blood-curdling  stories;  here 
the  kind  grandmother  came  to  see  if  we  were  comfortably 
tucked  in,  and  not  likely  to  fall  out  of  the  big  bed;  in  this 
little  wood,  along  these  alleys  that  seemed  endless,  we 
spread  our  nets  for  birds;  in  this  stream  we  fished  for 
crayfish;  there  on  the  path  we  played  at  soldiers  with 
our  elders,  who  were  always  captains;  on  these  slopes  we 
found  rare  stones  and  fossils,  and  mysterious  petrifac- 
tions; on  this  hill  we  admired  the  fine  sunsets,  the  ap- 
pearance of  the  stars,  the  form  of  the  constellations. 
There  we  began  to  live,  to  think,  to  love,  to  form 
attachments,  to  dream,  to  question  every  problem,  to 
breathe  intellectually  and  physically.  And  now,  where 
is  this  beloved  grandfather  ?  the  good  grandmother  ? 
where  are  all  whom  we  knew  in  infancy  ?  where  are  our 
dreams  of  childhood  ?  Winged  thoughts  still  seem  to 
flutter  in  the  air,  and  that  is  all.  People,  caresses, 
voices,  all  have  gone  and  vanished.  The  cemetery  has 
closed  over  them  all.  There  is  a  silent  void.  Were  all 
those  fine  and  sunny  hours  an  illusion  ?  Was  it  only 
to  weep  one  day  over  this  negation  that  our  childish 
hearts  were  so  tenderly  attached  to  these  fleeting 

336 


LIFE,  UNIVERSAL  AND  ETERNAL 

shadows  ?      Is   there  nothing,  down  the  long  length  of 
human  history,  but  eternal  delusion  ? 

It  is  here,  above  all,  that  we  find  ourselves  in  pres- 
ence of  the  greatest  problems.  Life  is  the  goal,  it  is 
Life  that  produces  the  conditions  of  Thought.  With- 
out Thought,  where  would  be  the  Universe  ? 

We  feel  that  without  life  and  thought,  the  Universe 
would  be  an  empty  theater,  and  Astronomy  itself,  sub- 
lime science,  a  vain  research.  We  feel  that  this  is  the 
truth,  veiled  as  yet  to  actual  science,  and  that  human 
races  kindred  with  our  own  exist  there  in  the  immensi- 
ties of  space.  Yes,  we  feel  that  this  is  truth. 

But  we  would  fain  go  a  little  further  in  our  knowl- 
edge of  the  universe,  and  penetrate  in  some  measure 
the  secret  of  our  destinies.  We  would  know  if  these 
distant  and  unknown  Humanities  are  not  attached  to  us 
by  mysterious  cords,  if  our  life,  which  will  assuredly  be 
extinguished  at  some  definite  moment  here  below,  will 
not  be  prolonged  into  the  regions  of  Eternity. 

A  moment  ago  we  said  that  nothing  is  left  of  the 
body.  Millions  of  organisms  have  lived,  there  are  no 
remains  of  them.  Air,  water,  smoke,  dust.  Memento, 
homo,quia  pulvis  es  et  in  pulverem  revertebis.  Remember 
oh  man!  that  dust  thou  art,  and  unto  dust  thou  shalt 
return,  says  the  priest  to  the  faithful,  when  he  scatters 
the  ashes  on  the  day  after  the  carnival. 

337 


ASTRONOMY  FOR  AMATEURS 

The  body  disappears  entirely.  It  goes  where  the 
corpse  of  Caesar  went  an  hour  after  the  extinction  of  his 
pyre.  Nor  will  there  be  more  remains  of  any  of  us. 
And  the  whole  of  Humanity,  and  the  Earth  itself,  will 
also  disappear  one  day.  Let  no  one  talk  of  the  Progress  of 
Humanity  as  an  end!  That  would  be  too  gross  a  decoy. 

If  the  soul  were  also  to  disappear  in  smoke,  what 
would  be  left  of  the  vital  and  intellectual  organization 
of  the  world  ?  Nothing. 

On  this  hypothesis,  all  would  be  reduced  to  nothing. 

Our  reason  is  not  immense,  our  terrestrial  faculties 
are  sufficiently  limited,  but  this  reason  and  these  faculties 
suffice  none  the  less  to  make  us  feel  the  improbability, 
the  absurdity,  of  this  hypothesis,  and  we  reject  it  as  in- 
compatible with  the  sublime  grandeur  of  the  spectacle 
of  the  universe. 

Undoubtedly,  Creation  does  not  seem  to  concern 
itself  with  us.  It  proceeds  on  its  inexorable  course 
without  consulting  our  sensations.  With  the  poet  we 
regret  the  implacable  serenity  of  Nature,  opposing  the 
irony  of  its  smiling  splendor  to  our  mourning,  our  revoltss 
and  our  despair. 

Que  peu  de  temps  suffit  pour  changer  toutes  choses! 

Nature  au  front  serein,  comme  vous  oubliez! 
Et  comme  vous  brisez  dans  vos  metamorphoses 

Les  fils  mysterieux  ou  nos  coeurs  sont  lies. 

338 


LIFE,  UNIVERSAL  AND  ETERNAL 

D'autres  vont  maintenant  passer  ou  nous  passames; 

Nous  y  sommes  venus,  d'autres  vont  y  venir, 
Et  le  songe  qu'avaient  ebauche  nos  deux  ames, 

Us  le  continueront  sans  pouvoir  le  finir. 

Car  personne  ici-bas  ne  termine  et  n'acheve; 

Les  pires  des  humains  sont  comme  les  meilleurs ; 
Nous  nous  eveillons  tous  au  metne  endroit  du  reve : 

Tout  commence  en  ce  monde  et  tout  finit  ailleurs. 

Repondez,  vallon  pur,  repondez,  solitude! 

O  Nature,  abritee  en  ce  desert  si  beau, 
Quand  nous  serons  couches  tous  deux,  dans  1' attitude 

Que  donne  aux  morts  pensifs  la  forme  du  tombeau, 

Est-ce  que  vous  serez  a  ce  point  insensible, 

De  nous  savoir  perdus,  morts  avec  nos  amours, 

Et  de  continuer  votre  fete  paisible 

Et  de  toujours  sourire  et  de  chanter  tbujours?* 

Note. — Free  Translation. 

How  brief  a  time  suffices  for  all  things  to  change  !  Serene- 
fronted  Nature,  too  soon  you  will  forget!  ...  in  vour 
metamorphoses  ruthlessly  snapping  the  cords  that  bind  our  hearts 
together ! 

Others  will  pass  where  we  pass ;  we  have  arrived,  and  others 
will  arrive  after  us  :  the  thought  sketched  out  by  our  souls  will 
be  pursued  by  theirs  .  .  . — and  they  will  not  find  the  solution 
of  it. 

For  no  one  here  begins  or  finishes :  the  worst  are  as  the  best 
of  humans ;  we  all  awake  at  the  same  moment  of  the  dream :  we 
all  begin  in  this  world,  and  end  otherwhere. 

*  Victor  Hugo.      Trtstesse  </'  Olympia. 

23  339 


ASTRONOMY  FOR  AMATEURS 

Reply,  sweet  valley,  reply,  solitude  ;  O  Nature,  sheltering 
in  this  splendid  desert,  when  we  are  both  asleep,  and  cast  by  the 
tomb  into  the  attitude  of  pensive  death, 

Will  you  to  the  last  verge  be  so  insensible,  that,  knowing  us 
lost,  and  dead  with  our  loves,  you  will  pursue  your  cheerful 
feast,  and  smile,  and  sing  always? 

Yes,  mortals  may  say  that  when  they  are  sleeping  in 
the  grave,  spring  and  summer  will  still  smile  and  sing; 
husband  and  wife  may  ask  themselves  if  they  will  meet 
again  some  day,  in  another  sphere;  but  do  we  not  feel 
that  our  destinies  can  not  be  terminated  here,  and  that 
short  of  absolute  and  final  nonentity  for  everything, 
they  must  be  renewed  beyond,  in  that  starry  Heaven  to 
which  every  dream  has  flown  instinctively  since  the  first 
origins  of  Humanity  ? 

As  our  planet  is  only  a  province  of  the  Infinite 
Heavens,  so  our  actual  existence  is  only  a  stage  in  Eternal 
Life.  Astronomy,  by  giving  us  wings,  conducts  us  to 
the  sanctuary  of  truth.  The  specter  of  death  has  de- 
parted from  our  Heaven.  The  beams  of  every  star  shed 
a  ray  of  hope  into  our  hearts.  On  each  sphere  Nature 
chants  the  paean  of  Life  Eternal. 

THE  END 


340 


INDEX 


Aberration,  300 

Adams,   168 

Agnesi,   Marie,   5 

Alcar,    34 

Aldebaran,  44,  66 

Alexandria,  3 

Algol,  39 

Ancients,  views  of,  30 

Andrew  Ellicot,  195 

Andromeda,  37,  38 

Angles,  289 

Antares,  45,  66,  70 

Antipodes,    208 

Arago,  275 

Arcturus,  39,  66 

Asteroids,    146,   195 

Astronomic  des  Dames,  9 

Attraction,  208 

Aureole,   279 

Autumn  Constellations,  54 

Axis,  225 

B 

Babylonian  Tables,  30 
Bartholomew  Diaz,  176 
Bear,  Little,  35 

Great,  32,  34,  35 
Betelgeuse,  49,  66 
Biela's  Comet,  189,  198 


Bode's  law,  167 
Bolides,   201 


Cancer,  72 
Capella,  38,  66 
Cassiopeia,  36 
Castor,  44,  68 
Catalogue  of  Lalande,  65 
Catharine  of  Alexandria,  3 
Centaur,  52,  64,  65,  80 
Ceres,    147 
Chaldean  pastors,  30 
Chaldeans,   271 
Chariot  of  David,  32 
Charioteer,  38 
Chart  of  Mars,  140 
Chatelet,  Marquise  du,  4 
Chiron,  The  Centaur,  30,  51 
Chromosphere,  102 
Clairaut,  3 
Clerke,  Agnes,  7 
Cnidus,  31 
Coggia's  Comet,  187 
Comet  of  Biela,  197 

of  1811,  186 

of  1858,   174 
Comets,   in,   185 
Constellations,  28 

figures,  of,  31 

Autumn,  54 


341 


ASTRONOMY  FOR  AMATEURS 


Constellations,  Spring,  52 

Summer,  53 

Winter,  51 
Copernicus,  125 
Corona  Borealis,  40 
Corona  of  the  Sun,  104 
Cygnus,  40 

D 

de  Blocqueville,  Madame,  5 
de  Breteuil,    Gabrielle  -  Emi- 

lie,  4 

de  Charriere,  Madame,  5 
Deneb,  41 
des  Brosses,  5 
Diaz,  Bartholomew,  176 
Dipper,  32,  34 
Donati,  187 
Double  star,  stellar   dial  of, 

86 

Double  stars,  68,  70 
Dragon,  36 
du  Chatelet,  Marquise,  4 

E 

Eagle,  41 
Earth,  205 

ancient  notions  of,  19 

distance  from  the  sun,  215 

how  sustained,  21 

inclination,  224 

in  space,  20 

motion  of,  round  the  Sun, 
222 

movement  of,  217 

rotundity  of ,  206 

viewed  from  Mars,  144 


Earth,  viewed  from  Mercury, 
119 

viewed  from  Venus,  130 

weight,   210 
Eclipse    of   Sun,   May,  1900, 

273 

Eclipses,  259 
Ellicot,  Andrew,  195 
Entretiens    sur    la    Pluralite* 

des  mondes,  9 
Equator,  225 
Eudoxus,  31 
Evening  Star,  123 


Faculae,  98,  100 
Fire-balls,  198 
Flammarion's    Lunar    Ring, 

253 

Fleming,  Mrs.,  7 
Fontenelle,  9 
Foucault,  219 


Galileo,  95,  98,  125,  244 
Galle,  1 68 

Globe,  divisions  of,  226 
Great  Bear,  32,  34,  35 
Great  Dog,   50 
Grecian  Calendar,  229 
Greek  alphabet,  33 

H 


Hall,  Mr.,  143 
Halley,  181 


342 


INDEX 


Halley's  Comet,  3,  175 
Heavens,  map  of,  61 
Hercules,  41,  66,  79 
Herdsman,  39 
Herschel,  Caroline,  6 
Hevelius,  246 
Hipparchus,  31 
Houses  of  the  Sun,  43 
Huggins,  Lady,  8 
Huyghens,    49 
Hyades,  44 
Hypatia,  3 


Janssen,   102 
Jupiter,    148 

satellites,  155 

telescopic  aspect  of,  150 


K 

Klumpke,  Miss,  7 
Kovalevsky,  Sophie,  6 


Lacaille,  292 

Lalande,  3,  9,  65,  292 

Latitudes,    226 

Leonids,   195 

Lepaute,  Madame  Hortense, 

3.  4 

Le  Verrier,  167 
Little  Bear,  35 
Little  Dog,  50 
Lockyer,  102 


Lbngitudes,  226 

Lucifer,  122 

Lunar  Apennines,  251 

landscape,  254        < 

topography,  252 
Lyre,  40 

M 

Mars,  131 

chart  of,  140 
Measurement,  289 
Medes  and  Lydians,  266 
Mercury,  114 
Meteorites,  201 
Meteors,  190,  191 
Metonic  Cycle,  271 
Milky  Way,  78,  87 
Mira  Ceti,  77 
Mitchell,  Maria,  7 
Mizar,  34,  69 
Moon,   232 

diameter  of,  242 

distance  of,  292 

geological  features  of,  245 

map  of,  247 

mountains  of,  246 

phases  of,   241 

photograph  of,  240 

revolution  of,  234 

rotation  of,  242 

size  of,  242 

temperature  of,   250 

total  eclipse  of,   263 


N 


Nebula,  in  Andromeda,  81 
in  Orion,  81 


343 


ASTRONOMY   FOR   AMATEURS 


Nebula,  in  the  Greyhounds, 

82 
Neptune,  65,  166 

revolution  of,  169 
Newton,   181 
Nucleus,  95,  185 


Orion,  48,  49,  81 


Parallax,  292,  293 

annual,  306 
Pearl,  40 
Pegasus,  38 
Penumbra,   96 

Periodic  Comet,  orbit  of,  182 
Perseids,  195 
Perseus,  38,  70,  78 
Phenician   navigators,    30 
Phoebus,  67 
Photosphere,   101 
Piazzi,  147 
Planets,  109,  113,  146 

distances,   no,  302 

orbits  of,  115 

orbits  of,  116 
Pleiades,  38,  39,  44,  83 

occultation  of,  85 
Pleione,  84 
Polaris,  63 
Pole-star,  34,  63 
Poles,  225 
Pollux,  44 
Pope  Calixtus,  176 
Prodigies  in  the  heavens,  178 
Ptolemy,  31,  217 


Radiant,  195 
Riccioli,  246 
Rigel,  49,  70 
Roberts,  Mrs,  Isaac.  7 


S 

Saidak,  34 
Saros,  271 
Satellites,  1 10 
Saturn,  156 

revolution  of ,  157 

satellites,  162,  165 

volume,  158 
Saturn's  rings,  161 
Scarpellini,  Madame,  7 
Schemer,  95 
Schiaparelli,  139 
Secchi,  Father,  7 
Seven  Oxen,  32 
Sextuple  star,  74 
Shepherd's  Star,  1 1 
Shooting  stars,  193 >  194.  196 
Sirius,   66,   309 
Solar  storms,  100 

flames,  105 

system,  65 
Somerville,  Mrs.,  6 
Spring  constellations,  52 
Stars,  distances,  62 

double,  68,  70 

first  magnitude,  57 

number  of,  60 

quadruple,  73 

second  magnitude,  58 

shooting,  193,  194 

temporary,  77 


344 


INDEX 


Stars,  triple,  7'2 

variable,  75 

weight  of,  313 
Star  cluster  in  Hercules,  79 

in  the  Centaur,  80 
St.  Catherine,  3 
Summer  constellations,  53 
Sun,  88 

houses  of  the,  43 

measurement  of   distance, 
297 

photograph  of,  96 

rotation,  99 

temperature  of,  105 

total  eclipse  of,  276 

weight,  1 06 
Sun  and  Earth,  comparative 

sizes  of,  93 
Sun-spots,  95,  101 

telescopic  aspect  of,  97 


Temporary  stars,  77,  78 

Three  Kings,  49 

Total  eclipse  of  the  moon,  263 

of  sun,  276 
Triangulation,  288 
Triple  Star,  72 


U 

Umbra,  95 
Universe,  22,  23,  90 
Urania,  8,  9 
Uranoliths,  201,  204 
Uranus,  162 


Variable  stars,  75 
Vega,  40 
Venus,  121,  296 
phases  of,  124 
Vesper,  122 
Victor  Hugo,  24 


W 

Weighing  worlds,  309 
Winter  constellations,  51 


Zodiac,  constellations  of,  46, 

47 
Zones,  225 


(5) 


345 


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